The big problem is that the RV manufacturers use the lowest grade of vinyl they can get away with that will last through the warranty time in order to save a buck. Cheap calendered vinyl that cost about $70 for a 50 yard roll has a 3 year outdoor rating (mid America average exposure condition), mid grade calendered vinyl has a 5 or 7 year rating runs about $90 per 50 yard roll, high quality cast vinyl with a 12 year outdoor rating costs about $325 for the same size roll, there are also specialty vinyls that can last even longer, but they cost much more and are harder to work with due to ultra aggressive adhesives.
Note I owned a sign shop for about 7 or 8 years back around the turn of the century.