You are in the same boat as I am. I had one lower cab corner that had been smacked and had at least 3\4 inch of bondo (original repair) after spending hours of stripping, treating the metal, and reforming with body hammers and dollies, I finally went with one fiberglass sheet over the top and beefed up the back. It will still hold a small magnet to the surface (if that is important) but unless I had access to a replacement corner or making a panel myself with days of tedious hammering and dolly work I doubt that I could of got it that close. The metal is stable and until a re-pop comes along it will stay that way.
