On my 2001 Damon Daybreak when the switch is off there is 12V power inside and the batteries are not being charged by the converter. With the switch on the batteries are being charged. It has a BIRD so the chassis battery is charged also if needed. There are those that may say you can't have 12V inside without the batteries on. But as you know, you can. Thanks for following up.
2014 KZ Durango Goldrush
2018 Chevy 2500 HD Duramax/Allison