It's not just north of Boston, there is hardly anywhere to publicly charge on southeast Massachusetts. I wouldn't be able to take a Tesla to outer Cape Cod and feel comfortable I would make it back. A supercharger somewhere around Wareham or Plymouth would be nice, Wareham probably better.
From the North drivers could take 495 or 95, even 93 to 24 south, hit the supercharger in Wareham and either continue South down 195/95 towards New York or continue traveling to Cape Cod.
From the South a driver could charge at one of the CT locations, then follow 95 north to Wareham and have plenty to make it to Cape Cod and back or to make it to a potential central NH supercharger.
Once leaving Boston on a New England vacation, it's going to get tough.
The town of Plymouth has a L2 charger and the Natick Mall has a 70A charger. Not sure if those really help...