Wax won't protect it from the sun. Only thing that does is under cover or coatings.
Further up north you are and cooler the the climate the more the angle of the sun the less the damage. Heat comes with the sun and in the Southwesst and Fla etc is worse.
I have no idea as to how much it would cost to prep and paint but perhaps worth investigating the new modern clear coats. My 15 year old pu truck is cared for but sits outside and still glistens. Polishing and waxing helps but it won't stop the sun rays.
Most new coaches and I assumed Towables use these new paints or coatings but guess not.