Pretty hard to do
We lived onboard over a couple of winters in New York City and being in the water helps a lot since it is not much below 30F (salt) and the air near the surface is kept a bit warmer too. On the hard the boat would be exposed on all sides to air that could be -20 and colder. Don't know if people live on boats all year in Montreal - there are lots of people doing that in Toronto which is similar in terms of weather (other than snowfall).
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.