You could use a liquid plastic with abs properties. If you are already looking for a good epoxy that will hold up this route might be cheaper. There are plenty of "marine" epoxies that don't have very good flex characteristics- not that it matters too much for this situation but it wouldn't be great if it cracked and fell out. A low viscosity epoxy will absorb into the wood (if it is bare) and probably provide a better hold. If you don't give a shit just throw some caulking or rubber cement in there and call it a day (no idea how well it will hold in cold temps though).
If you get a non UV protective epoxy, it wouldn't hurt to paint over it, but to leave it doesn't seem like it would be a huge deal (your skis probably won't turn into a 15 year old deck in a couple of months).