Never tried to start a generator a -30.
But I think I have a way to do it.
Get a Honda EU2000 or two, and simply don't let them get that cold.
Store them inside a heated space when they are not running. Pull them out and start them before it gets that cold whenever possible, and don't shut them off unless it's gonna warm up some. With an extended run tank, one will run 72 hours without refueling, and that can be done while it's running.
Heck if you have two of them, then one can always be warm a ready to start as the other one can supply the power till it's oil change time. Then start the warm stored one, make the switch and change the oil inside the RV. Yes it sounds like a pain, but extreme cold weather camping requires sacrifices.. And there are some gadgets that make oil changes on the Hondas easy and spill free. Not even a drop.