This is an excellent post, mooregm5, and it contains exactly what the OP needs to know before assuming he can live aboard in upper New York state year 'round. Well, except for the last part about living in Denver all winter.
Denver, while a mile above sea level, is certainly impacted by winter, but it is not nearly as inhospitable as you seem to suggest. Denver sits at about the same line of latitude north of the equator as Baltimore, MD, and has a much different weather pattern than the New York Lakes region. Were it not for the altitude in Denver, winters there would be quite mild.
When a cold front sweeps down out of Canada along the front range of the Rockies, it can get cold quickly, to be sure. But the longest period of such cold that I can recall was about three weeks when the temperature never rose above 0*f. Of course, I remember that because it was highly unusual.
The real difference, though, is the moisture content of the air. Colorado is, basically, a dry southwestern state, and receives annual precipitation of about 15.5" while Buffalo, NY receives about 38.5". That's the part that makes living year-round in upper New York state so miserable, even on land.
Your advice to the OP to reconsider his idea of living aboard year-round in the Finger Lakes region is spot on, mooregm5. I'm sure it wouldn't take him too long living on a boat when winter arrives before he abandoned the idea and went apartment hunting.
TaoJones