Photos of my rust issues (bed)

Here's some photos of the rust problems I'm dealing with. This area is normally covered by a plate that hides the damage. It's a very typical problem with many Rancheros. The plate actually covers the area that in a station wagon version of the chassis, would be the foot area of the rear seat. Ford had to put the removable cover plate to give access to the upper rear shock bolts. From the factory these are 'sealed' however if the shocks are ever changed the seams will leak. Once it starts you can't see the water sitting in the lower area and the rust starts. My plan is to use a rust stop chemical that will coat the edges then pop rivet a sheet steel patch over the larger areas. This will then be covered with fiberglass. Finally the whole bed (and the area under the cover) will be painted with bed liner. I'm also going to 'seam seal' the patches so hopefully this will slow down the rust so I can get another 20 or so years out of the vehicle.