You need to have more patience. I believe epoxy will stick to cured polyester...BUT in that area the bond to wood will never be stronger than the polyester bond. You'll probably be ok...but don't take that to the bank. I would probably sand one side off, go with epoxy/fiberglass, then do the same to the other side (unless the inside is only taped...then I'd leave that part alone). I've built boats using polyester, or epoxy...but have never combined the two. Epoxy is simply a much better product for building boats like we build.