The answer is "it depends".
A good quality converter or inverter/charger may not need a battery as a "filter".
But, there is a risk of harming PC boards if your converter or inverter/charger is not designed to be used without a battery in the circuit.
My recommendation is to either get the answer from your converter or inverter/charger owners manual or call the manufacturer and ask if it can be used with the batteries out of the coach.
Another option would be to remove the chassis battery and temporarily install it in place of the house battery. A little more work, but no more $$ or risk.
