You could put the hinge on a backer of wood or metal, long enough to span the two ribs in the wall and attach the backer to the wall framing. It only would need a piece of aluminum about 1/8 to 3/16" thick and maybe 1-1/2 to 2" wide. It could be screwed to the framing in the wall, but I wouldn't use pop rivets for it in this kind of situation. Pop rivets are okay for the hinge as long as you use all of the available holes.
If that doesn't work I have some other ideas
Rich