Ya, you would need to use a light compound for sure. FYI...be ready to do the entire trailer! Once you start its going to make a big difference and there will be no stopping point.
If you use a compound you'll need to seal it back up with a good wax. I've been using Satin Creme and it seems to work very well on my cars. Still need to do my newish trailer.
I bought one of these buffers when I was wet sanding my 340 hood. I was more than impressed with how it turned out. I plan to do my trailer this spring as it is long over due.