The only concern you will have with the epoxy primer is it has a relatively short recoat window in which the top coat must be applied for the chemical adhesion to work as designed. If you pass that window of opportunity you will either have to scuff it and respray with more epoxy or a sandable primer with better filling attributes before you paint your color coat. Epoxy primer does not fill scratches or voids very well. It does look a lot better than rusty metal though.
I would also suggest not leaving the primered parts outside uncovered for a long duration as UV, pollution and dirt will attack the primer over time. Should that happen to a significant degree you may have to re-strip and start over. Use a good truck cover if you do not have a garage or shed available.
