The epoxy primer can be painted, so unless there is sime surfacing needed, you don't need any more primer. What is the "regular" primer that is on the other panels? If you wanted to have a paintable surface, you could epoxy prime those "regular" primered panels and paint the whole thing. If the primer is lacquer, then you WILL want to epoxy prime them or remove the lacquer and epoxy prime. If you look at the tech sheet on the epoxy primer you are using it may say whether you can shoot it over the lacquer or not. Is there some reason you want to shoot the "fill prime" on the entire truck?
