I have an old 1982 Dodge xplorer camper van and have removed all the old fiberglass that was on the metal bed frame so that I could remove a ton of rust that was underneath. My plan was to clean the metal then spray epoxy primer to serve as a final coat and to protect metal from rusting while I spray foam insulation behind the walls, then seal it all up with fiberglass. So far I've already sprayed epoxy primer on 3/4 of the project area.. but i just learned online that apparently you can't fiberglass over paint?. Does this include Raptor epoxy primer? What I have is Bondo fiberglass resin which is polyester resin. Is there any chance that I don't have to scrape off all this expensive paint? Can't I just scuff the primer with 80 grit and fiberglass over it?? Thanks!