Ben, Lol... Ya, a boat tail would be fun. And in a way, it would be the easiest route because there's more control as a whole. But that is way out of my skill level at this point. I do plan on adding one to my future car though!
Even if I have to drive all the way over there to have you help me build it.
And a boat tail would be something I could add to RAVadoodle at any point. Speaking of attaching points, I spent some time looking at the top of the back door area last night, and there's no where to attach anything up there except on the door itself. The kammback might be a difficult project. But I'm getting off track!
A big magnet, and 1x2s is a good idea. I'll go that route if my other idea doesn't work.
I'm sure tempted to go the fiberglass route, and maybe for only parts of it. Would it be very expensive to get the supplies to do that?
Otto, if you're thinking of the "rear bumper cover" that is on the sides of the door, then that might be a possibility. Difficult, but where there's a will, there's a way. If your thinking of the grey area where the door is, then there's a bigger problem with that. Because that cover IS the door. In theory it would be a great idea, but I'm not going to loose access through the back.
The location that I attached the coro to, is inset from the edge of the RAV's floor, about 1.5". It's out of sight and a good thickness for screwing into. I'll open the back door and take some pictures so you guys can see what I have to work with. I'll also take off one of the side bumper covers to show that.