tsuru, here is an idea you might want to try. There is a ride in Ohio called the XOBA (cross ohio bike adventure) put on by Columbus outdoor pursuits. That is the exact ride they did this year, started in Kentucky near cincy and followed the underground railroad to Sandusky, ohio. It ended just a week ago, so my guess is the road makings and still there. They used images of the state of Ohio with arrows to mark the route.
You should contact columbus outdoor pursuits and see if you can get their route maps.