I keep my Class C on an RV pad in my back yard.
If you keep it plugged in, make sure you check the water level in your batteries every few weeks. Not sure why you would want it plugged in though.
Keep refrig off and leave the doors ajar (mine has plastic stops that hold the doors open slightly so air can circulate). Why are you planning on leaving the frig running? If you are leaving food in the rv, make sure you check for mice. I would empty everything food related and carry in what you need for short trips. Also check you owners manual for running refrig in cold weather, you may find outside temps may effect the efficiency when on electric verses propane.
Since it is not heated storage, things will freeze and cans and plastic containers may pose a problem. I had a soap bottle freeze and crack open. Glad it wasn't the olive oil!
If you are moving every few weeks, the gravel under the tires is probably ok.
I have MaxAir vent covers, so leave my vents cracked open so air can circulate around the coach too. I take mine out once a month, and check it at least once a week.
See picture in my signature. Last winter it sat there under all the snow from November to April! Hope this winter is better, but with the October Nor'easter, it doesn't look good! LOL