[folivier]

I used WashWaxAll for the 2 years we had our coach. I remained outside the entire time. Occasionally when road grime was really bad on the bottom I'd wash it with water. WWA was very easy to use and I was really pleased with the result. Others like Firecoat, which I still have the samples but never tried. Yearly I waxed it using Nufinish. I found these 2 approaches over 2 years worked great. Now however for the Tahoe I pay $15.00/month for unlimited car washes at the locally owned drive through carwash.
On the basement skins I did similar to Steve but used System3 Gel Magic epoxy 2 part. Unfortunately some of the skins were starting to separate after a year. To be honest my skins were much more separated than Steves. If I would do it over I'd remove the frame and old 3M tape and retape it again like Magown did. Much more work but probably a longer term solution. But if Steve's solution works then I'd definitely try it before it gets worse.