If you are going to build as a L1 cert then I would definitely use epoxy. There are portions of the build that demand epoxy, its just the way it was designed.
I am just a little ahead of you. Started doing the fin fillets last night. Using rocketpoxy and some micro balloons.
So far I have done 2 fillets and they came out really well. Hoping the other 4 go just as well.