For what its worth, a coworker has an old Connie and loves it, bought a custom seat for it and has been all over the country on it.
I would pass on the aluminum and floor tile.
Think of it this way. Your body gets ground by hundreds of pounds of force into the body panel you just repaired. What do you want that repair to be made of? Just how heavy and sturdy do you want it to be?
Those pics are too resolution for me to figure out what is going on.
If it were me, and it's a plastic or fiberglass panel you're fixing, I would stick with plastic or fiberglass, keep it the same overall thickness and strength as the current construction. Get your strength with overlap and lots of contact area on both sides of a very thin layer of high quality epoxy.