I know what you mean about the heat. I worked in the Nevada desert for 42 years. I have 5th wheel toy hauler with more glass. My large windows are dual-pane. The small ones are not. The third AC comes in real handy. It would get pretty warm in the garage without it. I set the garage temp on mine for around 85 degrees. There is no insulation in the wall between my garage and living room so my living room AC would probably run constantly without the garage unit keeping the temp in the garage down some. And with the black base color of the paint job, my curb-side wall would get hot. I have three awnings which cover just about the entire curb-side wall. This time of year, with the sun pretty high through mid-day, the awnings shade the wall down to the skirts, below living space. And yes, orientation should be considered if possible if you're out away from any help from trees. My electrical system has an energy management system that will allow the living room AC to run on demand by the thermostat at any time. The bedroom and garage AC units will run any time unless the other one is running. If both need to run at the same time, they alternate back and forth. With this system, you will only have two AC units running at the same time. One won't turn on until the other one turns off. That's why I set the garage temp higher than the bedroom. That way, the AC in the garage isn't demanding power all the time during the heat of the day. The living room comes on at any time. As you know, everything is a comprise. Look for RV parks that don't make you pay the power bill. And make sure all three units are 15,000 btu and not 13,000 btu. Also, you should consider having the Onan 7 kw gen set installed. If needed, it will supply the AC units plus the other items. The Onan 5.5 kw in just not enough for today's big power-hungry 5th wheel RVs.
