For those who know engines....

How often should I run the engine in my little motor coach?

I purchased it in Feb. Since then, thanks to the COVID, it has just sat in the driveway. The way the virus is spreading here in the mid south, I have no plans to go anywhere soon.

Same question for the aux generator?

Should I be starting these and let them warm up to operating temps?

once a month minimum. yes, let them warm up.

Always a good idea. Also use Sta-bil in the fuel.

I would also suggest driving it some to circulate the other fluids.

I think the battery is the only thing I would be worried about. It's not good to let them go without a charge for long periods of time. Maybe put it on a trickle charge once or twice a month. And as mentioned Sta-bil or Star-Tron in the fuel.

May be once a month, year round, start it up and take it for a drive long enough to get everything running and cycled.
Turn on the A/C, Run the heater (even in Summer) so the heater core doesn't rot out.

Make sure you also Simonize your Good Sam Club decal

Once a month is good for both. You don't necessarily need to get it hot, but you just need to circulate the oil and coolant. I'd also run the car around the block to get the transmission fluid moving a bit.

If your battery is over 2 years old, letting it sit for a long period is going to kill it.

Good things and bad things.
You have to start it to keep the battery up and the seals from getting brittle.
The transmission and AC need to be run. The AC really needs to be turned on at least every week so the o rings will stay good.