Crappy square body doors
 

I learned to do body work on a 72 Chevy truck. Thick metal and really curved panels that hold their shape even when dented. Now I'm working on a square body, 3rd one I've done, and every one the doors are garbage. The slightest dent and they oil can. I've tried hammer and dolly and shrinking with a torch. Every time I make it worse. Anybody else have any methods to make them rigid after they loose their stiffness? The spot I am working on now is on the top right below the window felts. Both doors have a low spot and are oil canning.