A/C couldn't keep up. Help?

Last weekend I spent four days living in my RV, parked in front of my daughter's house in Phoenix, AZ. It was approximately 115 degrees outside. I live in Las Vegas, NV, and it was similar weather here. Driving to Phoenix with my generator going the whole time, it was 99 degrees inside when we arrived (my dogs and I). The first couple days I ran either the front A/C or the back. Running my generator 24/7, the temperature inside in the front or back only cooled to mid to low 90s. I called on the 3rd day and talked to a repair person who told me I had to run both because they're ducted. I also went to Home Depot and purchased a Toshiba room A/C. With that helping, I was able to get to the mid to high 80s. I could not plug in to their house because they only have 15 amp. It kept tripping the breaker.

I don't usually travel in my RV in temps like this. It's a 2005 Fleetwood Discovery diesel pusher, model 35H. In the years up till now, I would only use the A/C a few times a year, just to cool down when it was maybe high 80s outside, and only for a few hours. I do dog agility and don't go anywhere that's really hot. When I visited Phoenix I wouldn't take the RV. Now I need to take my dogs and need to take the RV.

Last summer I let my ex-husband use the RV to live in while his house was completed in Pahrump, NV. The weather was in the 100s, and he used the A/C 24/7, hooked to electricity. Near the end of the time he lived in it, he said the motor was going out on the A/C, and he replaced it. (I had to buy it! :M)

Here are my questions: Do I need new air conditioner(s)? Do any of them work if it gets that hot? Is something else worn out from using it so much last summer?

Someone just suggested I get a roll of foam foil insulation for my windows. I'm going back to Phoenix in a few weeks and dreading the thought of living in that boiling hot tin can for another few days.

Comments or suggestions? Thanks in advance!