If you can get a Chademo adapter, that would be your best bet. Looks like you should be able to supercharge at Montreal, top up in Burlington VT via Chademo (there are a couple to choose from), Supercharge at Hooksett NH, and then top up in Portland ME (there are a couple Chademo chargers and a HPWC) before catching the ferry. A dash of level 2 in Halifax and then the Chademo in Truro will get you to the Island. Getting back could be a trick.
Eventually there will be a supercharger in Bangor (we have a Nissan dealer Chademo at the moment), and somewhere around Woodstock NB, but that could be a few years. At the moment plugshare doesn't show any Chademo chargers in NB, which is a problem. Going entirely in Canada via Quebec and NB, you'll be stringing together L2 chargers and RV park 14-50's. Good luck, Maine and NB are high-speed charging wastelands at the moment, I'm afraid.
-- BB - Canuck expat waiting on a Model 3