Been fulltiming for 6 years now in Wash State and all 3 Montana's have held up great BUT Yuma,AZ in the Summer YIKES!!! even with 2 A/C's that will be Harsh I am sure it is doable with Shades closed,foil in the windows,Slide toppers etc.. Maybee others have here and can tell ya how they can Manage it,But Hey you are a Marine you can handle it
and also In my experience the new Whisper air is not as good keeping the RV cool without some mods to the Vents which I have done as well as others to make the A/c work as it should