On that aluminum tonneau, why not slide it UNDER the rear roll cage bars and bolt through it?
Trouble is, it would have to be reinforced in some way to keep it from bending when you set things on top of it.
I have been looking at different things to build one out of too. Eventually I'll come up with something.
One of the things I want to be sure of is that I want my seats to be able to fully recline. On long trips, it's nice to be able to pull off, kick back and take a short nap. When riding passenger, it's a lot more comfortable while checking your eyelids for cracks.
I also want metal, not wood. Aluminum would be perfect. I want to fit my sub-woofer and amp into it along with a drawer that pulls out for putting my stuff in/
I like the idea of an aluminum tonneau that would fit on top of the inner fender wells.
The idea is forming, but I have to focus on the design.. Prolly this winter when I am plagued by cabin fever.