With my Flagstaff popup, the powerlift wiring is connected directly to the battery's posts with a auto reset breaker on the positive cable, right at the battery. You can leave the TV connected and that will supply enough to lift the roof, you do not need to connect to AC via a supply circuit or a generator.
Last year a friend of mine had to do that with his Flagstaff when he left the 12V fridge running on battery power over night in a hotel parking lot. (I told him to switch to propane.
) (And leave the TV running while the lift is operating.)
And I've always just pulled the two fuses (one for each B+ circuit of each battery) if the trailer is going to sit for a few weeks before use, and if over a month, I just pull out the batteries and run them home. Never bothered with a switch and never had a problem. But switch or no switch, the power to the converter has to be shut off if not camping.