It really surprises me that folks spend tens of thousands of dollars on their rig and then try and cheap out using Zeb or something else not designed for RV's.
I have been using PoliGlow for 5 years ore more repeating the annual coating as specified and counldn't be happier. My rig was somewhat chalky and faced (hardly a "basket case though"), when I got it (2005) and Poliglow has given me the best results. My boat gets the same treatment although I do occasionally need to strip the area where my fuel fill burps.
Yes $50 for 32 oz is more than the $5/gal Zeb but you get what you pay for in this case. One bottle will last me for years when only doing a coat or two every year.
Like others have posted I firmly believe that the preparation
is paramount.