For a variety of personal reasons I never had the time to follow this through.
I was unhappy with some left over pitting (didn't get aggressive enough at the coarse end) and 2000 grit was not fine enough. I've purchased some 3000 grit paper. I have not done any kind of UV topcoat yet and the lights are 95%+ better than when I started. They just aren't perfect enough yet to coat and apply film and consider them "done for life". They are certainly more than good enough that they do not stand out as an eyesore on an otherwise well detailed car.
There has been no yellowing or degradation since July, though my car spends a lot of its life in the garage. It's pretty much winter now and it's just going to have to wait.