The stock fuel tank on a 2004 Toyota Tacoma is only 18.5 gallons (70 L), which makes for a rather short range given my general fuel economy of between 13-16 mpg. I searched for a good place to mount a standard 5-gallon jerry can somewhere on the outside of my camper or truck, but just couldn’t come up with a good solution for something that would keep the weight forward of the rear axle. Ideally I would want to have that weight down low, but there was quite a bit of wasted space in the gap above my cab and below the cab-over section of the Four Wheel Camper. A regular jerry is just too big to fit in that space, so I needed something with slightly different dimensions.
I remembered seeing some really cool 1-gallon fuel & water cells for motorcycles from a company called RotopaX, and found out that they make a larger 4-gallon canister for vehicles. After checking the dimensions online, it seemed like it would be a perfect fit. And even better – they make a special locking mount for it! That way, it would be securely mounted to the vehicle, making it difficult for anyone to steal my extra fuel. I had hoped to not have anything bolted to the outside of my truck or camper to draw any unnecessary attention, so this would be an exception.
One major consideration for mounting this to the underside of the cab-over portion of the FWC is the bed slide-out on the inside. I would need to make the back side of the mount as thin as possible, but still have it be strong enough to handle over 30 pounds (about 25 pounds of fuel and 10 pounds for the canister and mounts). Along with the locking mount, RotopaX also makes a backing plate. However, the bolts they provided with it were quite thick, like a typical carriage bolt. I made a trip to my local hardware store and found some elevator bolts that would do the trick, with only some slight modifications.
Since these would be the first holes drilled into my brand new camper, I consulted with Chicali and Stan at Four Wheel Campers regarding anything special I should be aware of (such as wiring, framework, etc.). I must have measured half a dozen times before boring through the sleeping platform! The elevator bolts are completely round on the top, so no way to get a wrench on them to tighten the locknuts. So the first thing I did was to grind down two flat sides on each bolt. I then discovered that when inserted into the RotopaX backing plate, they sat a bit high so I opened up those holes a bit with a chamfered drill bit. Last, I had to grind down the bolts to the correct length so they wouldn’t cause damage to the RotopaX canister. With locknuts and Loctite, these shouldn’t loosen, even after hundreds of miles of bumpy roads.
The final touches on this installation included some caulking, taping, and sanding. I wanted to caulk up both the interior and exterior with a waterproof silicone so that moisture, dust, and bugs would not enter the camper. I also put some caulking around the elevator bolts and backing plate to help make them more flush with the floor so that the bed extension could more easily slide atop them. It was still a bit rough, so I sanded an edge of the wooden bed extension, which vastly improved the sliding without it getting snagged. Finally, I covered the plate and bolts with duct tape, making an even smoother surface for the extension to slide over.
I chose to situate the RotopaX fill cap towards the middle of the cab so that it would not be visible from the side of the truck, thus making it more difficult for someone to open and empty the fuel (since the cap does not lock). With a single locking mount, it’s impossible for someone to steal the canister, even when removing the non-locking mount. It is a bit difficult for me alone to lift up the 4-gallon RotopaX and tighten the mounts, but this isn’t something that I’ll be doing on a regular basis – only in emergencies when I need the additional fuel between fill-ups. I’m quite pleased with the end result of this modification, as it makes great use of wasted space and still keeps the look quite simple and low profile.