How many AC units are on the Mountainaire? It can really get hot there. I camped there one time in my trailer with high of 117, and I've seen it as high as 123F.
There will be a temperature rise in the interior in the afternoon.
It is not typically shady there, but if you can find a shady camping place you will be much better off. Nights can be in the '90s but the AC will work fine due to no sun loading.
For me an extended stay would depend on being in the shade, or not needing to occupy the RV in the afternoon, early evening hours. Perhaps with two or three good AC units in a class A, you would be better off than what I experienced in a trailer.
Swamp coolers are hit or miss effectiveness there due to frequent bursts of humid monsoon air. Quite a few homes in the area have both evaporative and AC installed-for any contingency. There can be periods of clouds and showers which help out the AC.