I lived aboard on Flathead Lake, Montana. I can only say a few things about winter on a boat. I use a small wood stove for heat. An "outfitters stove". The temp in my cabin was usually 80*F, even when it was 20 below outside. However...I figured out that the floor temp was about 30-40F. I could put my hand on the floor right under the wood stove. Ice and snow would not melt, but I had to keep the hatch open or roast. Get the heat source as low as possible, and sit with your feet up!
Hard and fast