I admit I haven't really paid much attention to this, but it seems to me that my EMS puts the second AC into "Shed" until the power draw settles down. Doesn't make any difference whether on shore or genny; it works the same.
When you drive I-15 thru Utah, you will notice regular is 87 octane in St. George (elevation about 2K') and it is 85 octane in SLC (elevation about 4.2K'). Every vehicle I have owned since 1980 has not had a problem with the fuel.