We just camped for four days in 100+ temps in Texas and after the first two days we realized that about 10am we needed to turn on both ac units (15000 in main area, 13500 in bedroom) and it would keep cool at 76-78 in both rooms. At night we would turn off the bedroom ac and run just the main room one as we aren't used to cold temps at night (we keep home unit at 78-80). Our unit is 40' long with ceilings that aren't low (not sure exact height). Our friends with a V-lite kept theirs so cold for him that she had to use an electric blanket at night. Theirs is 30', I think with lower ceilings but that's just not comfortable for us. We had 11 people over one night playing a dice game called LCR and it was very cool and comfortable (of course it was at night).
I just know that you need to keep it moderately cool at all times for the ac units to work adequately. If the rv gets hot inside, it takes a long time to cool down, at least for us.
2015 Coachmen Chaparral 360 IBL
2014 Ram 3500 Turbo Diesel 6.7 4wd Crew Cab Dually