I too live on board full time on the Hudson River, Haverstraw NY. This is one of the worst winters I can remember in this area due to the long duration of deep freezing temperatures. As I am writing this the forcast is for freezing sleet tonight and the date is March 30th and stil running heaters. I appreciate your writings about the snow and looking out the portholes and the charm of it all, and if you are going to lead this type of lifestyle here you have to appreciate the beauty of the natural world or you will crack up.
The temps were so cold that my marina had to put a second bubbler in my slip to keep me completely ice free. If you allow your boat with its external hung rudder to get completely ice locked you risk doing damage to the pintals and gudgeons as the ice melts and the boat hull moves and leverages against the rudder.
As far as fiberglass in ice vs. steel, the steel hull is much stronger than even our very tough Westsails, I would never want to completely ice my hull in.