After reading all the suggestion here I tried these as a test on the same day, same conditions, on my TT that is aluminum corrigated sides (not the smooth fibergass). I scrubbed quickly with a stiff bristle brush, imagining doing the entire side of the camper. We can call it the "Elbow Grease Factor". Lined up in order left to right of best results for MY enviroment.
* NOTE* The top hitter was a "white elephant" gift I won that was a piss-poor working chem on actual wheel brake dust remover but worked great on the TT. Some of the name brands may be too harsh to use as I have had them etch aluminum wheels in the past. Hope I can find more of this stuff.. Holey crap my TT has a shine under all that grime! Before pic as an example and last is the test showing the bottom two rows.
YMMV.