Hi Griffin
For what ever reason you decide to leave your boat in the water, the decision is yours.Here in Tennessee, most everyone winters in the water, but we don't have the long hard cold spells that you do. I winterize around November. I have one of those vaccume oil changers with a long slim hose that goes in through the dip stick. After going through the anti freeze flush, I'll snake the hose down to the through-hulls and suck the water out until I see anti-freeze coming through the tube. This is not necessary on all of them, just the ones like the raw water feed to the engine that has a fairly long run. Anywhere I can get to the through-hulls, I just disconnect the line and pour a little anti-freeze in before hooking the line back up. I've had folks laugh at me for doing this, but it just makes me feel better on those cold hard nights.Don't forget your fresh water system and hot water tank.Have you checked to see how thick the ice gets in your area?? Mike has a valid point. If the power goes out for an extended period, you might be busy for a while keeping the ice beat off.Good Luck!!