NetComrade, there are some on here who are fulltimers in the South who have sage advice for differing aspects of full time living. Others are passing along opinions they've heard others express. You're approaching this the right way--investigating yourself, getting some opinions, and research. In the end, it will be your choice and some of those who have contributed will be right, and the others will be wrong.
We spent from November through January in our "4 season" Heartland Caliber in the northern latitudes last winter after our house sold. We were further north than you--lows around zero--average around 30 (daytime high). We did not skirt the trailer (but should have). Propane (40#) about 2-3 days. Froze up the main water line (yes, it was heat-taped and insulated) once. Froze up the TT water lines (Heartland ran two lines in the very bottom of the underbelly) about 3 times before I slit the underbelly and insulated and heat-taped and insulated the lines. My black tank froze up once and I used additional heat and salt to thaw.
We were very comfortable both day and night. The furnace runs a lot, but we supplemented with electric heat. We kept a vent cracked to provide ventilation and reduce condensation. We would do it again in a minute, expect this time we would use a skirting of some kind.
