1999 Lance Lite for winter use.

Are you holding tanks in a basement or are they all in the main cabin. If they’re in a basement you’ll need to have some kind of tank heater for each tank. If the tanks are above the floor then they should be fine as long as you keep the temperature warm in the camper.

Another option is to run a furnace duct into the basement, and to ensure that the dump valves won’t freeze up.

Danny,
We have a 1998 Lance Lite 165-s xcab that we bought in 2001. These don’t have much insulation unless ordered with a winter package, which were very few and far between.
The best I can do in weather below about 22 degrees is to run the camper dry. No water in the water or grey tank and no running water. All tanks and water systems drained thoroughly including blowing compressed air through the lower reaches of the water pump. A few gallons on hand of minus 50 degrees RV antifreeze miserly poured directly into the toilet after each use as a flush. A lot of sturdy gallon and litre jugs of water placed in that floor cabinet near the door. With all the weight of the water pushing on the cabinet latch, I had to add another mechanical exterior latch to keep the jugs in place. 24-48, 16 oz bottles of water stored behind those little doors under the sink and fridge at floor level. An insulation job in all vents and behind cabinets. I used 1-inch molded R-11, foil faced, both sides closed cell foam cut to fit and glued to the walls behind the cabinets. Install at least 200 watts of solar on the roof. replace all 12v incandescent bulbs (12 on the interior) with LED’s which take only 1/10th the amps. All these upgrades do not equal a real 4-season camper, but allow you to survive without running the heater all night. Another winter item is a rubber floor anti slip mat under a cut-to-fit piece of pile carpet. This saves your tootsies day or night during winter months.
We turn the heater off in the night snug under a high pile goose down comforter and actually use sheets and blankets, which is nice. In the AM i get up and heat water for coffee and turn on the furnace once again. The total volume is so small, just the heating of water helps, with the caveat of opening a close top vent and cracking a window to let the water vapor out.
My biggest complaint about the Lance Lite is the lack of sufficient insulation.
You’ve got your work cut out for you.
jefe

It sounds like you actually do have the winter package with heated tanks. I’d say, try it out and find where the red line is. This can only be done with experience, not hearsay. If you can get down to about 05 degrees F without freezing your valves and hoses, you’re home free.
the other option is to run the wheels off your propane tank and maybe even have a spare tank to swap in over a two week period. We just refilled our 575 gallon propane tank on the property @ $1.69 per gallon, so it’s cheap enough to use. Another option is a catalytic heater in the box, but I’ve not had good luck with those in the past because of the exhaust smell.
This should be a fine adventure.
We found the lower limit in N. Nevada in January. Even running the propane heater at about 55 degrees, cycling on every 5 minutes or so with the lower cabinet door ajar, the dump valves froze @ 12 degrees. So, above that number is our personal lower limit.
With your setup, it may be lower. Experience will tell. The actual water pump is vulnerable to early freeze up unless the water fill valve box is well insulated.
jefe