Personally, I wouldn't take the chance. I have read about epoxy fogging after a while with exposure to the sun. Who knows if that will happen to you. You would have to be a chemist and have done studies of the epoxy brand etc. But considering all the work you have done, how long would it take to slap a coat of exterior varnish on it. The sanding might take a few hours and to coat it a half hour for the deck and half hour for the hull. Then you don't have to worry. The UV gets pretty intense in the summer and so does the heat.