After the epoxy cures I don't think you will have any problems at all. I like to let the epoxy cure for as long as possible anyway before sanding...at least a week...usually several weeks.
I use many of my boats for lengthy periods, sometimes months, before varnishing. The strip built I'm using now to learn marathon paddling hasn't been varnished for over 8 months. I haven't varnished it because of the need to make repairs quite often. I see no deteriation, or degradation, from sun or water damage with the epoxy I am using. Once I'm through abusing this boat...about may of next year...I'll refurbish it, recoat as needed, sand and varnish. It will be retired from anything but trips, cruises, camping and fishing. Kind of like an old race horse that was never very fast. No...wait...they make dog food out of race horses that weren't very fast