help with body work

My 92 is a rusted mess. I hate to junk it because it only has 41K on the speedo and the interior still looks almost new. I bought new fenders to take care of that area. I purchased door skins for the rusted bottoms of the doors. These come unprimed. The discription says that you can weld, rivet, or screw them on. If I riveted them on, would I just bondo over the rivet and then prime? I dont care if its not perfect. The point is to get rid of the rust and get some paint on.
Also these are quite wide and come up above the trim strip. What if I cut them to fit just below the trim? Then I wouldn't have the edge on top to deal with.