I’m going to be replacing some sheet metal on one of my vehicles soon. They come with the EDP primer. I read the post about testing the coating with thinner or acetone. Providing that the coating doesn’t just wipe off of the panel, should I spray an epoxy primer or etching primer over this coating? Also, when painting the panel (fender), should I go ahead and put a couple of coats on the inside to protect it from rusting? Thanks in advance for your help.