6 Best RV Slide Out Storage Solutions

You’ve seen it a thousand times—that wide-open, unused space under your RV’s slide out. It feels like a missed opportunity, a perfect spot for storage that just sits empty. Reclaiming that dead space is one of the biggest "aha" moments for new and experienced RVers alike, turning a forgotten zone into prime real estate. The right under-slide toolbox doesn’t just add storage; it organizes your setup and teardown process, keeping the dirty gear outside where it belongs.

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Unlocking Space Under Your RV Slide Out

That gap under your extended slide out is more than just empty air. It’s a dedicated zone for the grittier side of RV life—sewer hoses, leveling blocks, power cords, and tools. Storing this gear outside frees up your primary pass-through compartments for cleaner items like camp chairs and grills.

The challenge isn’t finding a box; it’s finding one that fits and functions without interfering with your rig. You have to consider three critical clearances: the space available when the slide is extended, the much smaller space when it’s retracted, and your overall ground clearance. A box that hangs too low can easily get torn off on a steep driveway or a bumpy backroad.

This is why you can’t just bolt any old truck box to your frame. The best solutions are designed with these constraints in mind. They use low-profile designs, robust mounting systems that attach securely to the I-beam frame, and in some cases, sliding mechanisms that make access a breeze. Forget crawling around on the wet ground—the right setup brings your gear to you.

Lippert Underchassis Storage: A Seamless Fit

When the company that makes your chassis also makes the storage box, you can expect a near-perfect fit. Lippert is a dominant name in the RV industry, and their Underchassis Storage units are engineered to integrate directly with their own frame systems. This takes a lot of the guesswork out of the equation.

These units are typically made of steel with a durable powder-coat finish, built to withstand the abuse of the road. They often come with pre-drilled mounting holes that align with existing features on a Lippert frame, making installation relatively straightforward for a dealer or a confident DIYer. The result is a clean, factory-installed look that feels like it was always meant to be there.

The main tradeoff is cost and compatibility. Lippert solutions are a premium option, often priced higher than more universal alternatives. And while they are perfect for Lippert frames, mounting them to a different manufacturer’s chassis might require significant modification, defeating their primary advantage of easy integration. This is the go-to choice for a seamless, purpose-built solution if you have a compatible frame.

MORryde Sliding Cargo Tray: Easy Access Champ

MORryde approaches the problem from a different angle: access. Instead of just a static box, their products are often sliding trays that extend out from under the RV. This is an absolute game-changer for ergonomics. No more kneeling in the mud to fish out a heavy generator or a tangled water hose.

These trays are built tough, designed to handle significant weight capacities—often 200 pounds or more. The smooth ball-bearing slides allow you to pull the entire platform out, giving you easy access to everything on it. It’s the perfect solution for heavy, awkward items like portable generators, large toolkits, or even a portable waste tank.

Keep in mind, most MORryde trays are not enclosed boxes. They are open platforms, so they don’t offer weather protection or security for loose items on their own. You’ll still want to store items in their own weatherproof containers. Think of it less as a toolbox and more as a heavy-duty drawer that makes your existing gear infinitely more accessible.

Stromberg Carlson Trailer Tray: Versatile Pick

The Stromberg Carlson Trailer Tray is the jack-of-all-trades in this category. It’s a simple, robust, and highly versatile tray that can be mounted in various places on your RV’s frame, including under the slide out or on the A-frame of a travel trailer. Its universal design makes it a popular choice for a wide range of rigs.

Typically made of steel mesh, this tray is great for items that need ventilation, like generator or propane tanks. It’s a straightforward platform designed to carry bulky gear. Many RVers use it to get their generator out of a primary storage bay, freeing up that space and keeping the fumes and fuel outside.

Like the MORryde, it’s an open tray, so it offers zero protection from rain or road grime. It’s also a very simple design, which is both a pro and a con. The installation is flexible but may require some drilling and careful planning to ensure it’s secure. It’s a solid, no-frills option for adding carrying capacity for large, self-contained items.

Torklift Lock and Load: Heavy-Duty Security

If you’re storing something valuable, security becomes the top priority. The Torklift Lock and Load isn’t just a tray; it’s a security device designed specifically to protect expensive gear like inverter generators from theft. It’s the Fort Knox of under-slide storage.

The system features a heavy-duty tray that mounts to the RV frame, but its key feature is an integrated, high-security locking mechanism. You place your generator on the tray, and a robust steel arm clamps down over the top, securing it directly to the platform with a puck lock. A thief can’t just unbolt the tray; they’d have to defeat the lock or cut through solid steel.

This is a specialized piece of equipment. It’s not for storing leveling blocks or sewer hoses. It’s an investment to protect another, larger investment. For full-timers, boondockers, or anyone who leaves their generator unattended, the peace of mind offered by the Lock and Load is well worth the premium price.

Dee Zee Poly Underbed Box: Lightweight Option

Moving away from RV-specific brands, we find excellent options in the commercial truck world. Dee Zee is a well-known manufacturer of truck toolboxes, and their polyethylene (poly) underbed boxes are a fantastic lightweight choice for RVs.

The biggest advantage of a poly box is weight and durability. Unlike steel, it will never rust, and unlike aluminum, it won’t dent as easily from minor impacts. This is a huge plus for something mounted low on your rig. The reduced weight is also a critical factor, as every pound counts toward your RV’s Gross Vehicle Weight Rating (GVWR).

The catch? These boxes are not designed for RV frames. You will have to purchase or fabricate your own mounting brackets. This requires a bit more DIY skill, but it also gives you the flexibility to position the box exactly where you need it. For the RVer comfortable with a drill and a wrench, a Dee Zee poly box offers a durable, rust-proof, and lightweight solution.

Buyers Products Poly Box: Budget-Friendly Gem

For the RVer who wants maximum function for minimum cost, the poly boxes from Buyers Products are tough to beat. They offer many of the same benefits as the Dee Zee boxes—lightweight, rust-proof, and surprisingly tough—but often at a more accessible price point.

These are no-nonsense, utilitarian boxes built for work trucks, which means they’re designed to take a beating. They are perfect for the unglamorous but essential gear: chocks, hoses, electrical adapters, and emergency tools. The built-in locking latch provides a decent level of security for low-value items, keeping honest people honest.

Just like other non-RV-specific boxes, the main hurdle is mounting. You are on your own to figure out a safe and secure way to attach it to your RV’s frame. However, if you’re willing to invest a little sweat equity into the installation, a Buyers Products box delivers the best bang-for-your-buck in under-slide storage.

Choosing Your Box: Size & Material Matter

Before you click "buy," grab a tape measure. This is the most important step. You must measure the available space with the slide out and with it retracted. Pay close attention to any slide mechanisms, wiring, or plumbing that could interfere. Finally, measure your ground clearance to ensure the box won’t bottom out.

Next, consider the material. Each has clear tradeoffs:

• Steel: Strongest and often very secure, but it’s the heaviest and can rust if the coating is compromised.
• Aluminum: Lightweight and rust-proof, but it’s more expensive and can be dented more easily than steel.
• Polyethylene: Lightest, completely rust-proof, and very durable against impacts. It’s often the most affordable but may offer less security against a determined thief compared to a heavy-gauge steel box.

Your final choice comes down to balancing three things: what you’re storing, your budget, and how much custom installation work you’re willing to do. If you’re storing a $1,000 generator, a security-focused tray like the Torklift is the right call. If you just need a place for your sewer hose and leveling blocks, a budget-friendly poly box is a perfect fit. There is no single "best" box—only the best box for your specific needs and rig.

Ultimately, adding storage under your slide out is about more than just creating space. It’s about creating systems that make RV life simpler and more organized. By moving the right gear to the right place, you streamline your setup process, keep your main storage bays clean, and make your small space feel a whole lot bigger.