Waterborne?
Not sure why you are using a waterborne primer but as long as you have put a adequate film build on the 'glass you will not need to coat during your test phase. After 22 years in the paint industry I have not used the Dupont 210S primer but for a few things. We used it for spot priming problem substrates that had an adverse reaction to solvent based materials. Generally it is best to spray a light epoxy coat on any fiberglass and then use a urethane type of primer-surfacer after you have filled any imperfections. Generally you have a 7 day window after the epoxy is sprayed to do repairs before you have to sand again, and per the manufacturers suggestion, to recoat with another coat of epoxy primer. Not sure why they call it a primer, more like a sealer to me. But back on the subject, In my opinion, I think you will be fine with the 210S, no neet to coat with anything, but when you are ready to paint for final time spray a nice coat of urethane primer and you will be OK.
