Body experts. Advice?

I don’t use POR at all on body panels! Areas that are rusted really need to be media blasted and cleaned and then use a weld through primer or if no repair is needed then use an Epoxy Primer. Body filler can be used on top of Epoxy...the only thing about Epoxy is...if your not gonna top coat it with paint or 2k primer and it’s over 24hrs since you applied it...you will have to scuff it with a scotchbrite or wet sand it prior to assure proper adhesion.