In a recent article, I lamented the competing pressures of efficiency and luxury in campers. I wanted something small, light, and efficient that my Bolt EUV could tow, because nothing spoils a fun trip like going into debt (both financial and to my kids for ruining the planet) to cover the fuel bill. But, living in the American cultural milieu where bigger is better and less is not more means the family would rather I buy a V8 or diesel pickup to tow a mini McMansion around. Sadly, the laws of physics don’t let you ask for forgiveness or pay the fine later, so having both is impossible with current technology.
I’m stubborn, though. I’ve been all over the internet trying to figure out how to build a TARDIS-like travel trailer with minimal weight and aerodynamic drag but with plenty of space inside to keep the family happy. I thought that maybe some company had advanced “space age” materials and an ingenious folding design to give us enough of both worlds to cover my needs and the wants of my family.
But, as I continued this search, I found out that it wasn’t the RV manufacturers or some innovative cleantech company that was on the case here. Instead, there are thousands of hobbyists building the lightest possible campers in their yards and garages, and some of them even expand to have more space inside. The exotic material they’re using? It’s called PMF, which sounds cool and trendy until you realize it stands for “Poor Man’s Fiberglass.”
PMF is actually very simple. Take some foam board (which already has excellent insulating properties) and cut the stuff to shape with a razor, a small saw, or tin snips. If you want better insulation in your camper, use thicker foam board for a minimal weight penalty. Glue your pieces together with Gorilla Glue or Foam Fusion. Then, put a material with tensile strength on the surface and glue it on. Then add more glue and paint get that stuff good and stuck, and sand/paint as needed to get the desired finish.
The strength of foam board is that it’s strong in one dimension. It’s floppy, but it can’t really be smashed any more the skinny way. Whole houses can rest on top of the stuff flat-ways. By putting a material like window screen (metal or fiberglass), canvas, or something else that’s thin but can’t be stretched (tensile strength), you’re covering for the foam’s weakness and making the finished product strong in the second and third dimensions.
The end result is a composite board, or even a whole composite structure, that’s both light weight and strong. How strong? Well, I’ll let this YouTuber show you:
In another video, he takes the “foamie” camper out on some even rougher terrain, even going as far as to ford a river. So, it’s pretty obvious that this construction method isn’t lacking anything when it comes to strength and durability. And, if you put the effort in to finish it right, there’s no reason it can’t look as good as any camper out there.
Light Weight Is Just The Beginning Of The Efficiency Benefits
One of the bigger benefits to this construction method is the flexibility it gives people, and all without requiring any power tools. Being able to easily build curved shapes in just about any size means that you can optimize for efficiency in ways that aren’t nearly as easy as with a wood frame and metal or fiberglass sheet siding. For example, some people in Arizona figured out how to build a camper that a 4.5 horsepower Vespa scooter could easily pull.
It’s also common for DIYers to start with cheap utility trailers from Harbor Freight and build a lightweight camper on top of them. Because the material is so light, it’s possible to build a much broader variety of campers on that platform, including larger but still efficient teardrop designs that any car can pull. Even better, there are some builders putting together expanding camper designs that give hard-sided travel trailer space while not being a literal drag to tow (aerodynamically speaking).
Expanding campers with hard sides aren’t anything new in the RV industry (the Hi-LO campers are a great example), but weights for these have generally been well over 2,000 pounds. With PMF “foamie” construction, similar designs can be made that weigh less than half that.
Another guy built a “foamie” camper atop a Tesla 85 kWh battery pack to act as a range extender for his Rav4 EV, and later a Model X. The battery pack is obviously not going to be light, but the lightweight construction of the foam camper on top of it allows for that to be less of a problem. Plus, it more than made up for any towing losses.
What I’m Considering Building
The “Slidavan” above is a great starting point, but it’s still small by my family’s standards. But, I could easily tow something that weighs double what it does with my Bolt EUV (this couple I wrote about recently proves this). A wider camper that sits about 5 feet tall folded down would still tuck nicely behind the EUV, and give 7-8 feet of headroom folded up.
Plus, I could build a rear slideout that pops up itself, and tucks inside the box when being towed. The rear slide could almost double the interior room when parked, kind of like a cross between the “Slidavan” and this contraption:
This would make for a lot more weight, but with just one slideout that pops up like the “Slidavan,” the weight would still land somewhere around 1200 pounds, which is still ultralight by American standards, but would give the wife and kids the room they demand.
Low Tech Can Still Be CleanTech
Compared to an EV or even something like the Aptera that’s built with advanced composite materials, this idea of building a camper with foam, screen, or cloth, and glue is primitive. But, light weights and flexible shaping can still give amazing efficiency and environmental benefits without using the latest “whizbang” technology out there.
Perhaps more importantly, it can give EV drivers with a family a camper they can tow, even with a budget EV like I drive. Being able to visit nature without screwing it up as much is a great thing.
The big question now is whether camper manufacturers will start picking up similar technology to do a better job of selling lightweight campers to the masses who don’t want to DIY it. If that can happen, we might see a big shift in the industry to support EV drivers.
Featured image by Phoenix7777, CC-BY-SA 4.0 License.
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