Papering fins just plain sucks.

I use NOS good-old-fashioned Aero Gloss Dope Balsa Fillercoat and Sanding Sealer.
You can get Sanding Sealer still from Brodak (just as good) or Sig (needs 1 part thinner to two parts sealer).

Epoxy is not generally used due to it being HEAVY.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !