This may not help you, but it may help others.

Here in the northeast, I live in MA (5% sales tax). I purchased a
boat from a dealer in CT (6%). I keep the boat in RI (NO SALES TAX on
boat purchases).

After extensively researching the legal twists to be sure that my plan
was sound, I formed a personal corporation in Delaware. This costs me
about $150 each year for corporation tax and a registration fee.

My dealer wrote the bill of sale to my Delaware corporation and filed
the necessary forms with CT to exempt me from paying sales tax. This
required that the boat be delivered to me outside of CT, so the
delivery was done 15nm away from the dealer in RI.

Now my own state, MA, would want to be paid the sales tax on this boat
that I bought in another state (CT) just because they feel deserving I
guess. Since I keep the vessel in RI, they can't collect. However if
I were to spend 60 days or more in MA waters, they would demand
payment. The same is true for CT- if I were to spend more than 60
days, CT would want to be paid. I think the number is 60 days, but it
might be 90- I'm not completely sure.

Now RI knows where their bread is buttered. RI does have a sales tax
of 6%, but they exempt this tax on all boat sales. This includes all
equipment, outboards, etc. purchased with the boat. I think the only
requirement is that the boat be kept in RI waters for 2 years.

Now RI isn't dumb. They have created a tax-friendly environment where
boaters get a break on a purchase but then pay taxes directly or
indirectly on boating supplies, meals in restaurants, and in general
contribute to the economic health of the state. Well, it works. I've
kept my boat in RI for 10 years, and have no intention of ever moving
to one of the money grubbing states.