We sail with a guy who has been a wind surfer for-ever. He was just talking about a spray-on product used to clean/clear old and foggy widows. I will ask him this weekend again about it. perhaps it has some UV/hydrophobic properties too?

I typically fall/jump/capsize through my windows before they fog up, and/or they don't last too long here in the fl sun and need tape/replacement (they aren't that expensive to replace)