Re: registration/insurance as a foreigner
Being from New York, I would advise in favor of registering in Maine. All other things being equal, people's attitudes toward your bus may be more favorable with a Maine or Washington plate than with one from New York. People see a New York plate, they think "Manhattan," "Wall Street," and "pushy;" not "dairy farmers" or "woodsmen."
Maine's registration is somehow different, and may be better. Most of the long-haul tractor-trailers I see on the Interstate highways have a Maine or Indiana plate on the semi-trailer, regardless of where the fleet has its terminals or registers the tractors. There has got to be a good financial or legal reason for them to go to the trouble to do this. I think they often use one or more licensing agents in Jefferson, Maine. It must be kind of like the lawyers' offices that register the offshore corporations' "headquarters" in the Caribbean islands.
Check it all out with your contacts.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.