Mossydan,
I am a former midwesterner living in Massachusetts. There are many great places to go. For MA and RI, the most productive times are during the late spring/early summer (late May through June) migration north and the early fall migration south (October). That said, the fish are around throughout all summer.
Not so sure about the jon boat idea, but it is worth a shot. If you get out early in the season, you can put it in some of the estuaries.
What part of the east coast are you considering?
If you want to PM me, I can point you to some forum that specialize in these areas.
Last season was a great season. It was not uncommon to take my boat out and land 20-60 fish in a 4 hour period.