Student at the Hard Knock School of Aerodynamics
Buddy of mine turned me on to this stuff called GACO. 100% silicone. Can be put in squeeze bottle to pour around roof vents, skylights, etc., or brushed on around the edges, or rolled on like paint for larger flat areas. He calls it the forever roof because you only need to do it once. I did mine last year and still looks new. It's pricey at $79/gal, but 1 gal did my 27' TT including the slideout. If you're tired of coating yours every few yrs with that garbage the RV companies sell, give it a try. Well worth it.