I’m looking to make multi-day (at least weekend but possibly longer) kayaking trips along the coast of New England. Are there any islands that are public and can freely pitch a tent on like I can backpacking in National Forests? I’m guessing only Maine will have something like that but I’m open to anywhere up in the Northeast.
You could try checking into Washburn Island in Waquoit Bay, Falmouth MA.
I go back probably 20 some years ago when we paddled Cape Cod regularly we did paddle Waquoit Bay a couple times. People were camping on Washburn Island. If memory serves me though you needed to make reservations.
Probably not much help. Good luck with your quest.
In Maine, join the Maine Island Trail Association. There are over 200 islands under their control, but you must be a member to camp on any of them.
There are very few islands anywhere that are not privately owned or that allow legal camping without reservations and/or permits.