Great pep work ... I also use 2 outside coats of resin and 1 to 2 inside coats before I fiberglass... It's always worked well for me
you're just wasting the effort of coating outside and the inside. Just brush the inside with "rondo".
the resin isn't a better substrate to put bondo on. Using rondo in the inside fills the corners and beveled areas hence it's better to do this alone before the filler. This is the most cost effective way to do it.If you do a coat of poly resin on the outside it will cover the holes, so you'll have a better rondo work on the inside, and it will also give you a better surface for the bondo (it will stick better to the helmet) plus a harder surface to work.