So you need to winterize while in storage in NC? Do you have power while in storage? Have you ever winterized the 5210? I need 5-10 minutes to winterize my 5211 outside of draining the tanks. I got a piece of clear tubing, put a connector on one end to screw onto the water pump and a little v-notch in the other end. I put the notched end into a gallon of RV Antifreeze. Makes quick work of winterizing the lines and fixtures.
Your options seem to be:
1) Winterize once, use other facilities as you mentioned.
2) No power and threat of hard freeze during 2 week stay in NC = winterize, then de-winterize when headed south. Evaluate each time.
3) With power, keep an electric heater inside the coach set to about 45 degrees. Open cabinets, etc. for airflow. Bypass and remove anode rod plug from WH.