I don't know what your incentive is to make the numbers favor NH, but its clear anyone who thinks NH domicile will save them 10k is using funny math. As my statistics professor always said, we can interpret the numbers to point to whatever conclusion we prefer.
If as you said, you're going to be a "true" fulltimer, with no homebase, & moving around the country; then neither winter nor state sales tax have any relevance to ones domicile choice.
SD winters are pretty fierce too, but none of the 100,000 SD based fulltimers need to experience those winter conditions, we're all down in Az, Tx or Fl for the winter. We go back to SD once every 5 yrs to renew our DL, and if your birthday is in a winter month you have 6 months before or after(by request) to go in for your renewal. Likewise, lots of SD resident fulltimers have friends & family in other areas of the country where they spend time each year. Your domicile state has nothing to do with where you like to spend your time while traveling, as long as you stay on the move.
As a fulltime traveler, how do you save $5000-$8000 in NH sales tax when you're rarely in NH or any other state long enough to benefit from a lower sales tax. That leaves your claimed vehicle insurance savings being offset by the higher registration fees. With the only real difference being in medical insurance costs, which unless you're on Medicare or covered by a past employer, is a rats nest of ongoing changes for everyone in any state. I haven't seen anyone saving $4000 in ACA premiums by just changing states. In many states the premiums vary by County more than they do from state to state. Who knows, if your number is accurate maybe you'll start a mad rush of folks moving to the "live free or die state". When I was stuck back east as a young man, I always enjoyed ice climbing on Mt Washington every winter. But these days a sunny beach is much more attractive winter destination.
Team Bologna wrote:
Jim, I'm perplexed as to why you'd think I would fudge the numbers. What's my incentive to do so? Picking a state that's not winter-friendly certainly isn't a good decision if it doesn't legitimately have a reason.
That said, New Hampshire saves us:
$5000-8000 in sales tax, versus other states
$1000/yr in truck/RV insurance
$3000-4000/yr in health insurance
It's much more expensive in vehicle registration, but for the vehicles we have, it only amounts to about a $1500 loss to the other states.
Ken