My name's Peter, I'm new to this board. I'm an avid recumbent cyclist and I love bicycle touring. I've toured for years with the standard cycle touring equipment, that is, a tent, air mattress, sleeping pad, etc... But since I currently live in Belgium, and the low countries (that is northern Belgium and the Netherlands) are flat as a pancake, I thought it was an opportunity to build myself a camper trailer to go to the seafront with my bike and camp out at the beach in style in the summer.
In the winter, I'm also planning on trying to go up the Ardennes and go ski with it, but I'll see how much of a handicap the weight is going to be in the mountains.
So, that's the rationale for my silly project. I've designed it as a 8 ft long, 3 ft wide, 4 1/2 ft high trailer with a somewhat aerodynamic shape (well, let's says "rounded" more than aerodynamic) that I'll pull behind my Quest velomobile. I've finished the chassis, bed and wall frames. Here's what it currently looks like:

(if you want more photos, videos and the build's history, read this thread on the BentRiderOnline forum)
So now I have to install a door and a window, and skin it. That's where I have a problem.
What's important with this trailer is to make it as lightweight as possible. I'm only an average rider, and I can't put out much more than 200W for hours on end when I tour. Already the trailer weighs 120 lbs and I reckon it's far too much.
As you can see, I've designed the walls to be rather lightweight. I originally planned to skin them with Coroplast, but the material is a pain in the butt to glue to anything, which means I'll have weatherproofing problems.
Now I've pretty much decided on skinning it with heavier, but easier to work with, 3 mm wood panels and 2 mm clear PVC sheets for the non-opening windows and skylight in the middle, then weatherproof everything with one or two layers of fiberglass and epoxy, then white gelcoat. But I'm concerned because even when the roof panels are tacked on, the walls will still be rather flexible because they're so thin, and I'm concerned that the epoxy and/or gelcoat will crack.
Also, again because the walls aren't very rigid, the door and the opening window won't press on the rubber joints hard enough and water will seep inside. I can always go with a commercial sliding window and door such as the ones from these guys, but again they won't be very lightweight.
So, I'm not sure what route to take to skin my camper. Do you think the fiberglass+gelcoat idea would work despite the amount of flex in the walls? Would there be another solution that would be more appropriate in your opinion? I welcome any idea you may have!