To be honest, there are easier ways to pop a roof!
The Carawagon roof, although looking fairly simple in design, wouldn't be the easiest project to start from scratch - measurements are really critical to get everything lifting/folding correctly, and the alloy panel isn't mere aluminium (which would work harden and crack with repeated bending & straightening) but a special alloy.
BigDave on here has recently replaced his alloy sheets with the correct material, so perhaps a PM to him might be a starting point.
Before I got my first Carawagon I was intending making a lifting roof similar to an X-Panda
HERE.
Although tht brochure is for a SWB, I couldn't see why the same design couldn't be used for a LWB.
Note that the X-Panda hinges at the back - I assume because the top of the screen wouldn't be strong enough to take the full weight of the roof. My intention was to make a rectangular steel or alloy box frame, something like 3"x1" to add strength and then hinge the roof on the frame at the front, which I think would be more useful internally.
Of course, if you really want the classic look of a Carawagon roof, I'm sure someone with a Carawagon near you would let you have a good look and take measurements
Cheers,
Robin.