Try Salisbury State Park In MA. There are also 2 private campgrounds in the vicinity of the SP.
Stay away from the CG in Gloucester unless you want to climb hills with loaded bike.
Wells SP near Sturbridge, along with private along RT.20.
I Can send you my cue sheets from Portsmouth NH to Springfield MA if you wish.
I am on Warmshowers and you could camp here.
Also have back roads & rail trails sheets to NYC
ED