landyacht318’s comment on alternator output seems to be a problem on many coaches and most isolator’s experience a voltage drop that compounds charging problems. A nifty solution that has worked well for us is to connect an inverter to the starting battery and run an extension cable from it to a 3-stage battery charger (Guest type) that’s wired to the house batteries. This provides plenty of amperage to the batteries when you’re driving and just plug in shore power (generator) directly to the charger when you’re boondocking. It’s a simple set-up that the Aussie’s use quite a bit in the outback.
The only A/C we use comes from the 1200-watt inverter in the rear of the coach or the extra receptacle in the 600-watt inverter up front that charges the house batteries.