I have a thought! (First one this year)
In view of the failed bypass proposal, I can see a narrow gauge park-'n-ride revenue producer just waiting to be harvested or jumped on or slaughtered!
A parking lot and auto-train loading facility could be constructed at the 218 crossing, with a similar setup on the east side of the Sheepscot at the route 1 crossing.
Daily departures from either end could whisk trainloads of impatient auto folks around that pesky highway bridge!
We could avoid the common carrier complications by pointing out that such service on a two footer is quite uncommon!
In keeping with "Precission Railroading", which is all the rage these days, I think distributed power is the way to go, sprinkling Henschels and tiny Baldwins throughout the train. Throttle commands would be transmitted via state-of-the-art bell cord, or chord, if multiple bells are employed.