Hi Don:

How about not bothering to epoxy the painted side of the hatch at all. Just apply a clear oil based varnish over top the graphics assuming they are compatable (test again). If you are really bent on covering it, we sign guys use a waterborne primer (clear) known as TI-COTE that allows you to paint oil based paints onto vinyl. It's made by Chromatic and is sold at sign suppliers. Just keep in mind many wooden boats were made before the days of epoxy and still sport some handsome finishes.

Doug