Um, thanks for asking.
But if we weren't, we'd be in a hotel. Seriously, folks,, 80 square feet isn't hard to heat, though you do have to take some things into consideration. First of all, since most boats are poorly insulated, air leaks are an issue. We've crammed discarded foam into every crevice we can find in the evenings to make sure we don't lose the heat we have.
|Some gonzo foam insulation we stuff in the hatch when we button up for the night
The confined space of a V berth, covered over with hard, uninsulated fiberglass, is a formula for condensation. You're in there, you're breathing, and your breath condenses on the ceiling. It's not impossible for it to rain. No foolin.
In the original Floating Empire, we had a problem with condensation collecting between the ceiling fabric and the membrane which could suddenly result in a waterfall . . . .of course, directly over the bed. Here aboard Tesla's Rvenge, there's less of a gap in which water might collect, but still the roof above your head can glisten with water. It can get unpleasant. Partly, we solved that with a small, Peltier device dehumidifier that did a great job of removing moisture from the small space (see here).
Of course, with the first of the cold winds coming on, we took the gizmo out of storage to discover that it's power supply had shorted out. Ah well.
Right now, it's comfy inside, with our new insulation in place, and some candles going, and lots of blankets in the V birth. We'll be snug and fine.
Winter aboard a boat is at the same time a problem and rather simple. Insulate the drafts, deal with the condensation, and you'll be fine. Frankly, we're looking forward to it.