I built a 10' hybrid a few years ago.
I started with a tent trailer deck and reinforced it, then added a heavier axle and springs, then bigger wheels. The floor (my one concession to weight) was 3/4" marine ply, glued, screwed and undercoated. I framed up the coach from steel studs and sheathed it with 1/4" ply and used epoxy and 6oz cloth over that. The most expensive part of the project was keeping the beer fridge stocked because I always had folks coming by....the trailer itself probably cost me less than $1000 to build.
I scavenged the windows and appliances from a guy who was parting out a slide-in camper that lost a battle with a low overhead in a drive-through.
Dave Grason wrote:In fact, I've often thought why don't trailer builders glass and epoxy their trailers just like the boatbuilders do.
Having seen the construction of this guy's camper, my motorhome, and checking out new units for research - I gotta say:
some of the crap that's out there is downright criminal. On my moho, the walls were framed with 2X2 studs....pretty common right ? Well remember that a 2X2 is actually 1 1/2" square. Anywhere that they needed to run wires, they drilled a 1" hole through the framing ! No chafe protection either. I guess the monkey in the fab shop had only a single 1" spade bit....
This was for everything from a 3/4" water hose that was too big but was jammed through the hole anyway, to a single pair of 18ga speaker wires in the roof !
Were I to do it again, I would make up my own 'glass panelling by laminating a piece of Formica to a sheet of plywood then wax and polish it. Gelcoat goes down first, then a vinylester & veil layer to back that up, then a layer of mat for strength. Once it's cured, it can be bonded to the framing with a polysulfide adhesive/sealant like 5200 or Sika 291. To prevent any large panels from oil-canning and spidercracking the gelcoat over time, cardboard tubes ripped in half lengthwise and glassed over within the wall space make a great and cheap stiffener: the tubes from gift-wrap and wallpaper work great. With an extra 2" strip of Formica added around the edges of the 'layup table', you could create a rabbet in the finished panel that would let you join the panels invisibly with 4" glass tape. It would have to be faired and painted afterward rather than gelcoated ahead of time though...it's tough to do a gel repair in a big flat panel and have it look good.
The 'hybrid' part of my design was a fold-down front panel that made up the bottom 5' of the bed - the 24" bench seat gave me a 7' long X ~5' wide bunk. I went this route rather than a slide out bunk like on a tent trailer so that I'd have the hard shell and could still drag the trailer into fishing holes and use it as a 'warm-up/lunch shed' while fishing even if I wasn't spending the night.
The whole thing came in at about 500 lbs IIRC before the appliances went in. Making fiberglass panels would easily save another 100 lbs in plywood and lexan windows would be even lighter but I'd still use ply for the roof. There's also a product called 'Italian Light Ply' that's lightweight, if a little pricey. I'm not sure what species the veneers are...spruce maybe ?