I've sealed several tanks with Caswells but never one like this.. '77 CB550, which has the flat keyed flap and the inner gas cap. Previously, with the "pop up" caps, I've just stuck a latex glove flat over the hole and closed the cap, which held the glove in place and didn't allow the epoxy to get on the rubber cap gasket. Can I do the same with this one, or is there a better way?