This came up some months/years back and I suggested possibly the worst idea in recorded history. (I just heard that phrase recently) It is to buy two Sunshield tarps or maybe only one. Put them both on the top of the RV. The lower one would have the dark side facing up. The top one would have the dark side facing down (white side up). The thinking is that the lighter top side would reflect the sun and the layers between the tarps and between the tarp and roof would act as insulation.
Open the Maxxair vents and the end windows for air movement.
The tarps come in various sizes so get one that hangs down from the roof enough to cover the decals.
We hold ours down with six boat fenders half filled with sand.
Dick_B
2003 SunnyBrook 27FKS
2011 3/4 T Chevrolet Suburban
Equal-i-zer Hitch
One wife, two electric bikes (both Currie Tech Path+ models)