One other thing I'm not sure about: I already have a 120V -> 12V power converter which charges the coach batteries when plugged in to shore power (and when running the generator, if I had one). If I get an inverter installed, it seems like that whenever the inverter is on, the converter guy would start pulling 120V and redundantly charging the batteries (which of course are being drained to provide that 12V in the first place).
So pretty much turning my inverter/converter loop into an inefficient heater. Any good solutions for this? It's kind of like I want the power converter to be wired on the "shore power" side of the system, and have that side isolated from the rest of the 120V system by an isolator, so the converter only kicks in when real shore power is being used?