I am a few slips away from you and know your boat well (at least I think it is your boat) since we have similar DNA. I tracked temps last year closely and I ended up with no worries about freezing in EBM as long as we had some heat going in the boat. The low water temp is about 45F although a thin sheet of ice can form-rarely-on the surface. Your engine compartment is surrounded by this “warm” bath (current temps are in the low 50’s). In the forward stateroom we keep a dehumidifier going, which warms that part of the boat, and a pancake air circulator in the salon. With our massive array of windows, any sunny day bakes the cabin and pilothouse, which is great for keeping things dry (we also leave our curtains up). Never had a worry about freezing. Not so up on Lake Union in the freshwater.
The bigger question is the mechanicals. Many of our neighbors take advantage of a sunny day to come down to the boat and run the engine at high idle for a half hour. They also exercise all of their systems (head, heat, gen, thrusters, etc.). In talking to them they are abiding by the adage “the worst thing you can do to a boat is not use it”.
Finally, we try to exercise the boat every couple of months. Here is a recipe when work and weather allow. Head across to Blakely Harbor (5 nm), drop the hook with a gorgeous view of the Seattle skyline. Have lunch and run the genset. Head back to EBM. Three hours and your boat will thank you with no surprises this spring.
In my last breath on this earth there is one thing I am determined not to utter: “if only I had spent more time in boats.”
BTW: your boat looked gorgeous in the clear cold weather this weekend, with Mount Rainier and the snow dusted Olympics in the background.