depends i guess.. on how your RV is wired
there is NO real reason to do it
of course there is always somebody that wants to warm the engine check his trans fluid etc,, while parked and connected and does not want to turn off his A/C
if you are that person, i suggest you turn off the inverter and the converter charger, flip the circuit breakers, then there will be only one source of 12DC power the alternator charging the batteries
the potential problem is low chassis batteries, pulling on the converter for power when you push the EMG start switch while plugged in and charging
i would hate to burn out an inverter/charger combo unit trying to start an engine
