I can't imagine doing this in Toronto. I have no experience in this, but what happens if there is a power failure, or any of a million other possibilities to knock out the system? How much time do you have before that lake crushes your hull like an egg shell? How often do you visit your boat in the dead of winter? If you can't detect and correct a problem in a lot less time than it takes to freeze up, I think I'd get a very good insurance policy.
It's hard to imagine but there's a community of about 500 boaters in the area who are year-round liveaboards, many winter on the water year after year. I wouldn't even try this if I wasn't living aboard myself, which I'm doing now. You are correct that you need to constantly monitor everything.
This would be my first time wintering on the water. I intend to ask some of these winter liveaboards and will let everyone know what the answers are. I do know that a 3/4 HP Ice-Eater will give me a 60 foot radius in ordinary conditions according to the maker, but the maker says nothing about under what conditions, so how does that work out in a Canadian winter of -30 Celsius...?