There would be no problem with MMO and Stabil. I've heard MMO is good for keeping gas fresh, but I think Stabil is better so I use both. The only thing I would suggest is drive the car vs. idling it. For some reason just idling a car doesn't seem to warm the oil up enough once it starts getting cold outside. A nice 30 minute drive early on a Saturday or Sunday morning, will burn off any moisture so there is one less thing to worry about.
The battery tender is a good idea, block up the exhaust and air intake to keep unwanted creatures from moving in, and put a few dryer sheets inside the car to keep it smelling fresh. I'd figure you already have a good coat of wax on the car
JMO,
Frank D