The cheater box will not work in most CG. If the plug CB is GFI, it will trip it. I have run both of my AC at most 30 amp hookups and not dropped below 115 volts. Sometimes I get down to 112 volts. I know I can only run two major appliances at once so if we want to run a MW, hairdryer or other high draw item, we turn off an AC, until done.
I have a Kill-A-Watt (you can get them from Lowes, Amazon or other home center with electricity section) plugged by the door to check periodically. If it gets to 110 volt, I switch fridge to gas and turn off 120volt items or I turn off an AC as appropriate.
This will vary, based on the size of your major items (AC, MW, Hairdryer, W/D). Draws will be different.