When I'm asked about the feasibility of wintering over on a northern island, I give the same advice as I would if asked whether a person should buy a motorcycle. If you are of an age that you still bounce when you go down--then go for it! An island in winter floats in a sea of ice. As with a motorcycle, you will inevitably take a tumble. One moment's lack of attention, and you can find yourself standing on a sheet of black ice, doing a quick two-step on the way to horizontal. A broken bone is no fun at all.
On the other hand--winter is a magical time. Lots to see, and you definitely have the lake to yourself. Be prepared with lots of provisions--as there will be times that you can't get to shore. That said, it is worth trying as long as you bounce!