I am trying to complete one of Nick's Microbootlegger kayaks, my first strip build. Hull and deck are stripped up and off the forms. I have been procrastinating due to mild anxiety about fiberglassing the thing, and now I am running out of warm summer weather to complete it. I built the boat using the rolling bevel technique, and that produce a good-looking exterior surface, but not a uniformly perfect looking interior. My plan is to fair the interior by filling gaps with epoxy thickened with phenolic microballoons, level everything adequately, fiberglass, and paint the area visible through the cockpit opening. the outer surface of the boat will be finished bright.

My question: leaving cosmetic concerns aside, just how smooth and flawless does the interior surface need to be in order to properly apply the fiberglass? Over much of the interior, it will, of course, not be seen by anyone, so just how obsessive do I need to be for a structurally and functionally satisfactory result?

Thanks for your indulgence with this beginners question.