If I used my trailer regularly in high heat conditions, I would definitely look into a 2nd air conditioner and only staying at 50 amp hookups. The AC and inadequate insulation, along with leaks around the side seals make these rigs hard to cool.
I have 1 air conditioner. My wife and I once parked the rig at a California Central Valley park one late afternoon where the temp was 104 degrees. I left her in the air conditioned truck cab, set up the trailer, turned on the AC for 72 degrees, and went to visit relatives. When we came back 4 hours later the temp was only down to 87 inside.
Last year, on my way from Cody, Wyoming to the Gillette rally, me and another Heartlander got lost through following our GPS's and ended up on about 25 miles of red, dusty dirt, washboard, road taking a "shortcut". I was the rear trailer driving through all the dust stirred up by the first one. I had a bunch of open windows (I had forgotten about) in the trailer. When I got to Gillette it seemed like I had about an inch of red dust throughout my trailer.