Best way to slow it down is get something to shade that area from the sun, than go talk with a paint shop they could tell you want to do best and apply some good wax to this area for now.
Here in Vegas I was looking at a typical RV carport but to block the whole RV from the sun and have my slides out it was going cost a ton of money so I built a shade structure for a lot less $$ and now my RV does not get any direct sun to damage the outside, you need to add some shade material to your RV carport and protect it from the sun.
