I have been thinking about this for a while now! Spent Days researching different coatings and still haven't decided on one.

My roof is one pice as well and last year when I was on top replacing the AC unit I could not touch the roof it was so hot. Mine is basically uncoated aluminum with a calk seal around the edge. I was replacing the AC unit because it wouldn't cool the trailer down...... It is a 13.5k btu and the new unit wont cool down the trailer either.

It is insulated on the side walls, but not the front one for some reason. Not sure about the roof, that is why I was thinking about coating it. Glad you posted this today. It helped me make up my mind

-Dave