In this work session, I washed (with acetone) and primed the flap parts using Rustoleum's Self Etching Primer. The weather was in the upper 30's, technically too cold to prime, however once I sprayed the parts, I warmed them up in the garage just long enough to be able to flip them and prime the other side. I also too the opportunity to dimple the upper skins for the left and the right flap.
