We do it all the time. The inside surfaces of all my hatches (seacraft), the ice box, anchor locker, bilge, etc, are all coated with pigmented epoxy. It moisture and fuel "proof".
I use about 10% by volume pigment to epoxy, some pigments are more opaque than others. You should be able to get full coverage with two thin coats.
here is a picture of the bilge area before bonding down the sole
