If you dont want to do it again, only sand to about 800 and then clear them, it will give the clear something to bight into.

a lot of people us USC spraymax 2K clear, it has a high UV protection in it. its a 2 part spraycan so you only have like 24hrs to use it once you puncture the can.

most of the other stuff is just a temp sealer that wont last 6months or overpriced junk marketed just for headlights so its big money

I have had great luck in the past, do a quick search and a little reading.