6 Best Undercarriage Tool Storage Solutions

You’ve finally organized every cabinet and decluttered every drawer, but that bulky toolbox is still sitting in the middle of your living space. Every square inch inside is precious, and sacrificing it for tools you only need occasionally feels like a waste. The answer isn’t a bigger rig; it’s looking down, under the floor, to the untapped real estate of your chassis.

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Unlocking Space: Why Undercarriage Storage?

That empty space between your frame rails is more than just a void; it’s a storage goldmine. Tapping into it means you can get bulky, dirty, or rarely-used items out of your primary living area. Think about it: greasy tools, muddy leveling blocks, or extra sewer hoses have no business being stored next to your linens or food.

Moving heavy items like tools and jacks to the undercarriage also has a significant impact on your vehicle’s center of gravity. By storing them low and centered, you improve stability and handling on the road. It’s not just about creating space—it’s about creating a safer, more balanced rig. This is one of the few upgrades that enhances both livability and drivability at the same time.

Buyers Products Steel Box: Heavy-Duty Pick

When you need sheer toughness, steel is the answer. The Buyers Products boxes are built like commercial-grade equipment because that’s their origin. They’re designed for work trucks, which means they can handle road grime, impacts, and heavy loads without flinching. The drop-down door and T-handle latching system are robust and provide a solid seal against water and dust.

The main tradeoff with steel is weight and maintenance. These boxes are heavy, and you absolutely must factor that into your total vehicle weight calculations. While they come with a powder-coated finish, any deep scratch can expose the steel to the elements. If you live in a wet climate or use salted roads in winter, you’ll need to stay on top of rust prevention with touch-up paint. This is the box for your heavy-duty jacks, chains, and large wrenches.

Dee Zee Poly Tongue Box for A-Frame Trailers

If you have a travel trailer, the A-frame tongue is often a dead zone. The Dee Zee Poly Tongue Box is purpose-built to fit perfectly in this triangular space. It’s an incredibly efficient way to add storage for things you need access to when hitching or unhitching, like wheel chocks, leveling blocks, and hitch locks.

The high-density polyethylene construction is its biggest advantage. It’s incredibly lightweight, so it won’t drastically affect your tongue weight, and it will never rust. Period. The downside is that poly isn’t as secure as steel or aluminum. While it has a lock, it’s more of a deterrent against casual theft than a high-security solution. It’s perfect for stowing gear, but I wouldn’t store my most expensive power tools in it.

Weather Guard Aluminum Box: Premium Security

Weather Guard has a reputation for a reason. These aluminum boxes are the go-to for professionals who need to protect thousands of dollars in tools, and that security translates perfectly to the small-living world. Their locking mechanisms are some of the best in the industry, offering serious peace of mind if you’re storing valuable equipment like generators or cordless tool kits.

The aluminum construction offers the best of both worlds: it’s significantly lighter than steel and naturally corrosion-resistant. You get durability without a huge weight penalty. The catch, of course, is the price. Weather Guard boxes are an investment. But if you’re carrying expensive gear or traveling frequently through areas where theft is a concern, the cost is easily justified. Think of it as insurance you only have to pay for once.

MORryde Sliding Cargo Tray for Easy Access

Sometimes the problem isn’t the lack of a storage bay, but the inability to reach what’s at the back of it. The MORryde Sliding Cargo Tray solves this brilliantly. Instead of a box, this is a heavy-duty sliding platform that you mount inside an existing undercarriage compartment. It allows you to pull your entire cargo load out into the open, eliminating the need to crawl inside.

This is a game-changer for accessibility. Imagine pulling a 100-pound generator out with just one hand. These trays can hold hundreds of pounds and glide smoothly on ball-bearing slides. The installation is more involved than a simple bolt-on box, as you need to secure it firmly to the floor of your storage bay. It also doesn’t add new storage space, but rather makes your existing space infinitely more usable. If you already have deep, hard-to-reach pass-through storage, this should be at the top of your list.

Valterra EZ Hose Carrier for Long, Thin Tools

Here’s a creative hack I’ve used on multiple builds. The Valterra EZ Hose Carrier is designed to hold a sewer hose, but its long, tubular shape is perfect for other hard-to-store items. It’s an ideal spot for fishing poles, long pry bars, leveling-jack crank handles, or even a small bundle of PEX pipe for emergency repairs.

These carriers are inexpensive, lightweight, and easy to mount directly to the frame rails. They come with lockable end caps, offering a decent level of security for low-value items. You can even mount two or three side-by-side for very little weight or cost. It’s a perfect example of repurposing a simple product to solve a common storage headache.

UWS Underbody Tool Box: A Versatile Option

UWS boxes are a common sight on work trucks and for good reason—they offer a fantastic balance of quality, weight, and price. Typically made from diamond plate aluminum, they provide good durability and corrosion resistance without the high cost of a premium brand like Weather Guard. They are a solid, reliable choice for the average user.

What makes UWS so versatile is the sheer variety of sizes and configurations available. You can find a box to fit almost any open space on your chassis. Whether you need a small box for tie-down straps or a large one for a full tool set, there’s likely a UWS model that fits. They represent a strong middle ground, providing a significant upgrade from a plastic tote without the extreme weight of steel or the high price of a premium security box.

Installation Tips and Weight Distribution

Mounting an undercarriage box isn’t something to take lightly. Never, ever mount a heavy box by screwing it only to the thin floor of your RV or tiny house. The vibration and weight will eventually cause it to fail. You must bolt it directly to or through the main steel frame rails of your chassis. Use large washers or a steel plate on the inside to distribute the load and prevent the bolts from pulling through.

Before you drill a single hole, get underneath and inspect everything. Look for wiring harnesses, plumbing lines (both water and propane), and brake lines. Also, check for clearance during suspension travel and sharp turns. You don’t want your new box to collide with an axle or tire. A good rule of thumb is to have someone bounce the suspension while you watch the clearance.

Finally, think like a cargo pilot. Where you place the weight matters immensely. Adding a 100-pound toolbox behind the rear axle of a trailer can reduce tongue weight and induce dangerous trailer sway. Conversely, adding too much weight in front of the axles can overload your hitch and tow vehicle. The ideal location is as close to the axles as possible, which minimizes the effect on handling and balance. Always re-weigh your rig, especially your tongue weight, after adding significant storage.

Ultimately, mastering undercarriage storage is about more than just adding a box; it’s about thoughtful design. By choosing the right solution and installing it correctly, you reclaim valuable living space and create a more functional, balanced, and capable home on wheels. It’s a foundational step in making a small space truly work for you.