Yesterday I finished the first cut of polishing my roof yesterday. I had an 8' ladder, positioned sideways as close as possible to the trailer without touching it. I went to the third step (last "safe" one), rotated 90 degrees, and reached my arm out, holding the compoound polisher out so that it just barely reached the centerline of the trailer. It took a while, and I am now stronger and sore in my arms, but it worked.
Required zero scaffolding, special tools, jigs, whatever. I just had to have a small vintage trailer and be 6'3" with long arms.