use rubbing compound its on the outside I promise its 2 bucks from anywhere you rub it ir and buff it off rub it on and buff it off run it on buff it off it will be crystal clear I bet ya a new set of headlights.
Lots of different plastic cleaners that will work great. His idea would probably work ( rub comp) because I had a crown vic that had the lights hold moisture & turn yellow. I wet sanded them back to life. Looked new. I drilled a hole in the bottom so water couldnt re-enter & one hole on the back of the light. It let small amounts of wind travel through it without letting water in & I never had moisture problems again.