My short shot gun is 26”. DBLThe key for all of these is do not start, stop or end in a state where your gun is illegal, and follow teh FOPA rules (gun locked separately from ammo, both in the trunk and preferable packed in separate luggage so they aren't visible.
Your carry permit means nothing for a good chunk of the trip, so don't even bother thinking about it. The good news is that both VT and NH are Constitutional Carry, so you are good once you get there.
The best thing about New England is the states are small, so you can get across most. I would stop in Pennsylvania for the night, then blast through to NH that next day.
And leave the 'short' shotgun at home... there no need and even in 'free' states NFA-tweakers like the Shockwave can get you in hot water, no matter what the court finally decides. Do yourself a favor and leave the toys at home. A good pistol and a couple of extra mags is all you need and no one can argue about how they are classified.
Thanks everyone for your comments.