Well, I took my CA trip in August. It was 109 in Vegas when we pulled in there. It was late afternoon and the trailer was very hot from being closed up and traveling. Fired both AC units up ASAP and got the inside temp down to 85 or so by bedtime. Used a portable fan to help circulate some cooler air into the bedroom.
According to my Progressive EMS I was pulling 32 - 35 amps. So, I ran a cord out the window for the 2nd AC and plugged into the 15 or 20 amp outlet on the pedestal. This was a 50 amp park, so no park power problems.
Went on to CA the next day. It was still hot, but maybe not as hot. I think I was getting erroneous readings on my outdoor thermometer, but I think it was generally around 100 degree days.
In CA, the 2 units were generally able to keep up, especially if no one was home. The day or two we were there I think we were able to keep the indoor temp to 78 or so, with it being noticeably warmer upstairs in the bedroom. This 78 actually seemed quite a bit more comfortable then what we experienced on our last CA trip. The CA park was a 30 amp only park, without any additional plugs on the pedestal. I know I was pushing the limits of the power source, but I never tripped a breaker. I do have an EMS that would have shut down if the voltage dropped too low.
Overall, I think having the portable in the back corner is an acceptable solution. Especially since I already had the unit. But, it is also much easier then trying to install another roof top unit on a trailer that is not wired for one.