Old thread, but I'll put in a coupla cents. I'd like to do something like this, only with hard sides. My old Apache pop-up had panels that dropped inward as you lowered the top. I've also thought about building an A-frame pop-up. There's a company that makes them, but way out of my budget. The center of the roof lifts up to form a letter 'A', and hard panels fold up and out to support the roof. Maybe build it on top of an old canvas pop-up. As I get older, and thinking about heavy weather or wild animals, the idea of canvas doesn't appeal to me as much.
That being said, I also had an idea for a teardrop camper. Classic canned ham shape, split along the beltline. Hinged in the front; the back raises up to give standing headroom. A canvas filler panel fills the gap. In really bad weather, you wouldn't have to pop it up.