Master shut off

Maybe...it depends on the RV wiring, as Harvey51 says.

On my Coachmen class C, the converter is connected to the battery side of the shut-off solenoid, so it will charge the battery with the shut-off switch turned off. It will also not power the camper 12V system obviously.

More common I think is for the converter to also be disconnected from the battery by the shut-off switch. This nearly has to be the case if the converter is built into the electrical center with the 12V fuses etc. as is frequently the case.

It depends how the switch is wired. I wired the shut off switch so it cuts off power to all loads in the house. I also have a fuse in the positive wire to the battery so I can disconnect that to isolate the battery from loads and charging.

I would kind of like a switch to conveniently (at the driver's seat) turn off the refridgerator when at a gas station.

What is your goal?

Negative

Nope

no