I have a 2015 Alpine 5th wheel. It was at the repair shop for 4 months after returning from a 3 month trip this winter in UT. When we brought the trailer home the awning which is white on the unders...
Open the awning, spray it with water, spray tilex all over it and roll it up for an hour, unroll spray it down with water and done. If its really bad do the process again..makes it like new without using a ladder, scrub brushes etc...