I lived aboard in Boston Harbor for about five years, then moved to Winthrop for several more. The relative hardships are easy to adapt to and each person will find their own levels of 'want' and 'need'. I personally only used heat during the day and only when I was aboard. I never used heat at night - too dangerous, in my opinion - you will NEVER make it out alive if anything goes wrong. Of course, there are safe heating solutions, but they are not only inordinately expensive, but prone to failure and doubly expensive to repair. I am not grousing - I have been in Yacht Service and repair for 20 years and am just sharing experience. Warm clothes trumps $5000 espar systems every time.
Never allow a Spartan existence to affect personal hygiene. Arriving at work sparkling and fresh every morning is hugely important to your own sense of well-being. I sometimes made the mistake of foregoing the cold and miserable morning shower and paid for it by feeling like a homeless dude living under a bridge. People at work would sometimes offer me clothes and food. It seems funny now, but it wears on you.
I lived in the new (then) East Boston marina next to the old Cashman yard where the floating drydock resides. At the time, I was the ONLY liveaboard there in the winter.
I sort of cringe at some of the boats you're mentioning, but to each his own. Remember that a large boat which you only use part of, still requires all the work and expense of it's size, including heat. Better to get a smaller, better boat that will be easier to resell should this foray into the salty end sooner than you think.