I went with the Thetford combo for my TT.
1) Rubber Roof cleaner in the manual spray bottle. I still have some left in the bottle after 2 uses. I used it with the long-handled soft brush.
2) Wash and Wax - I used it with the same brush (after rinsing the brush well).
3) RV Wax - This is the spray on, immediately wipe off variety. I can see the water beading off anytime I'm rinsing the RV (even without doing a wash).
Since I typically only do a full wash on the TT 1-2 times a year, I'm OK with spending just a little more for RV-specific products (especially since I bought them during a Thetford promotion at CW last year).