Suggest a star tour rather than a linear tour: establish a 'headquarters' in a city (a city like Dayton Ohio or Washington DC). This could be a motel or a campground (one with your all-important toilet).
This doesn't match your geographic constraint, but my first thought was also a star tour with a headquarters or home base. However, my first thought was an island such as Martha's Island in Massachusetts. Fewer cars to worry about and relatively flat. If not that, I'd look for something with similar attributes: rail trails or areas with lower vehicle counts, vacation areas will have things to do (though perhaps pricy).