Practice first in your driveway before it starts to get really cold. If it looks possible, practice on even colder forecasted nights, until you know your limits.
Buy some wireless remote thermometers and put them near your tanks, drain valves, water lines, battery compartment and outside.
Drain your water lines (but leave the hot water heater full and bypassed) then pull your camper out of your nice heated garage and test how the camper does overnight in the driveway by reading min / max the next day. This will give you an idea whether you need to winterize or not
Use a fish scale and weigh the easy to access 30# propane tank before and after to calculate propane use @ 4.2 lbs per gallon
Set the furnace thermostat for a comfortable 70 degrees, turn on the refrigerator and turn on the hot water heater.
Reset your battery monitor (i.e. Trimetric) and see how many amp hours (Ah) of electricity your use. If you don't have one then seriously consider buying one to manage your batteries. In the mean time use a voltmeter to read your batteries state of charge before and after to see if your batteries will make it. If less than 12.1 VDC the next morning, the answer would be no.
Spend the evening in the TC and use lights like you plan, Lights and the furnace fan use the most electricity. See how much electricity you use.
If you are going to do this a lot, consider adding insulation to your TC to use less electricity for the furnace. Think filling the holes in your TC like the big opening in the roof via the AC, the range vent, electric cord box.
Adding reflectix between the windows and curtains, and stuffing into skylights and fantastic fan vent openings. Adding insulation under the mattress also makes for a more comfortable night. Search this site and you will see how other Lance owners insulated their TC for winter use.
Replacing lights with LEDs also saves a lot of electricity, if you haven't done so already.
