There are not many, very few in fact, rv’s designed/capable of cold weather use with water in the system. If you chose to have water in the system, make sure you have one of the one’s those that have enclosed/heated tanks/lines and sewer dump valves.
We love winter camping, but, having a unit winter capable unit has it’s problems. New, they are unaffordable for the most of us, the better units going for well over $100K...except for perhaps the Arctic Fox 5th wheel.
Weight is also the byproduct of high insulation/well constructed units......ours weighs 20K pounds with all of our gear/water, ect. The majority of the really well made units, ceased to exist with the market collapse of the late 2000’s. All that said, there are many well maintained units for sale at a small percentage of the original price. Our unit went for about $160 K new....we got it at 8 years old, for under $35 K from a motivated seller! memtb