The Walmart in Framingham allows overnight parking. (Might work on the night into the area and save you a night of camping). Sounds like quite an adventure you have planned - try to work Minnesota into the agenda if possible. The North Shore (Lake Superior from Duluth to the Canadian border) would be worth a week or two of your time.
We find that it isn't as expensive as we thought to travel in the RV. With gas well below $3, we don't spend that much more on the road compared to at home.
Safe travels and enjoy. (I stayed at the Nassau County CG next to Old Beth Page Village on LI). Great location and decent CG.
Todd
