I painted my trailer with HC-2500 Amerflint II polyurethane from Tamco paint. It's been in sun and snow year around for 3 years and still looks like it did the day I painted it. It's excellent...I'm painting my glider with it this month.
https://tamcopaint.com/products/dura...30875014496336 . You have to wear a passive carbon filter mask that traps organics while spraying, but it's no big deal.
Excellent customer service, too.