Help with gelcoat over epoxy wood putty

[Tommy 1]

Hello my name is Tom. I am attempting to recondition a 1960ish canned ham camper. It was homemade, 1x2 framing with 3/8 plywood walls. The previous owner stripped off the fiberglass skin and then sold it to me. I reglassed the camper and then discovered a very annoying mistake. Rookie mistake . I used epoxy based wood putty to help hide the fiberglass seams. Some of the small blemishes were not a problem .. The larger seams will not accept gelcoat. I've tried scrubbing and washing the epoxy and sanding with 80 grit . Still no luck. Does anyone out there have a suggestion/solution, short of grinding it all out and starting with a different filler.
Thanks for any and all suggestions.

[FRED SMAILES]

I hope all read this problem of using epoxy.
I don't have any experience with this problem but I'm thinking maybe a spray sealer of some kind.
Someone in the auto refinishing trade may be able to guide you. I'm sure there is a product that will stick to epoxy and accept a gelcoat topcoat.

[Tommy 1]

Thanks Fred, I'll look into that idea. You are absolutely correct about the hobby.
I am gaining a lot of wisdom.