We're in the market for a class A. I've been shying away from dark-colored coaches in the belief that they would tend to run hotter. This is especially a concern because the coach I'm most interested ...
All RV roofs are white. Insulation is the issue; not the sidewall paint. Also get double pane windows. Side window awnings help a lot. Parking orientation also helps. Keep the front window out of the mid-day sun. Use window coverings. Many things to keep the RV cooler.
We never found it an issue with our motorhome. We were still able to boondock comfortably in the 80's. When it gets to the 90's we move to cooler places.