Both of those are my concerns as well, Allen Wrench. I've recently come across a pair of 12" all steel rims, from a jogging stroller, they're better built than the wheels on the bike trailer I've drug for 1,000 miles so far. I'm thinking of using all four in a tandem setup, but more likely, I'll use wheelbarrow wheels, like you say, shorter, wider wheels, which should hold the weight much better as well. Regardless of size and type, would the wheels be better served outside, or inside like he's using them? I would think inboard, but the wider stance should help with wind issues.
Also, mine will be wider than his, hopefully a more continuous arc. I'm hesitant to employ a spoiler of any type, as an errant eddy in the wind could be more disastrous than simply fighting it. If windspeeds are too high, I'll just crawl back in and wait them out. I also plan to leave the front flat, one because I have no idea how to calculate the curving cuts needed to produce the "airstream" nose, and two, because it will allow more interior room. If someone can help me with the geometry, I'll do the curved front, otherwise it'll be a rolling quanset hut.
Picked up a few small pieces of coroplast yesterday, they measure 12x18 and one is the new tool box for my bike, or will be. This was my first time working with coro, and I like it! After I reinforce the box, I'll secure it to a rear rack, which I have to pick up tomorrow. Very easy material to work with, I was also impressed with it's strength, especially when arched.
I may start a new thread for ideas an inspiration before the build. I've been given a standing invitation to go to Florida and hunt the Burmese pythons that are running rampant in the everglades, and I'm trying to talk the oldest of my brothers into joining me. If he builds a bike, I'll build him a camper too, so when I start the actuall build thread, you may get two examples. I'll extend my offer here, build a coro camper and be ready come fall.