The ones I have seen use the PolyC instead of resin to adhere the fiberglass cloth or Koverall to the airframe. PolyC is clear, so there would be no point in putting it over resin/glass. The resin leaves a harder finish, but the PolyC is still much more durable than a film finish.

For whoever asked about latex paint, AFAIK none of it is glow fuel proof. It is gas proof, so if you are using gas engines, latex is the perfect finish. For glow use, you do all your color/trim painting then shoot a coat or two of a fuel proof clear. Unfortunately, those ARE toxic and stink a lot, so that needs to be done outside or in a paint room/booth.

Mark