Living in the northeast, I have taken my Octane to FL in February, overnighting at Cracker Barrels and Wal-Marts on the way to/from. The furnace would warm up the trailer well for the overnights.
My water system was winterized prior to leaving home but I use a 3 gallon jug with a spigot on it, placed on the kitchen counter next to sink. I use this for washing hands, cooking and washing utensils. In the bathroom, I keep a 1 gallon water jug to use for flusing toilet (since the water is off). I also keep a jug of RV anti freeze to add into black water tank as well as kitchen and bath sinks to prevent freeze ups in the "P" trap.
I have used this method before in my previous campers when winter camping at year round sites. Another thing I used was a counter top model coffee maker (older metal, percolater style) that hold about 2 gallons. Great for keeping hot water ready for anything.