Our Greyhawk has only one rooftop A/C and some days I wish we had a second unit. I pay close attention to the orientation and shading of the RV when camped. Obviously shade from trees, especially afternoon shade, significantly reduces the A/C load.
The rig's orientation makes a difference, too. When in a sunny site, it is better if the awning side is on the west. That way I can deploy the awning to put the RV wall in the shade.
Cold beer helps with hot weather, too.