We recently had film (from 3M) professionally installed on all our window glass (while it was apart for restoration). A few air bubbles here and there, a few wavy spots - but so far we think it's worth it. We chose one that's nearly clear when held up to the light. Hopefully it won't look too tinted from the outside, which I think always looks out of character on an old trailer.
Should be much less glare, and it blocks 99% of UV light. Additionally, we used a "safety film" for the front windows (we don't plan on using a rock guard) and a heavily frosted film for the bathroom window.
All of this is installed on the inside of course, so it should last a nice long time.