I know you said you aren't interested in KOAs, but we have stayed at 2 along that route that might be ok for brief stops for you.
We ended up at the KOA in Wapakoneta, Ohio for a couple nights several years ago, not having planned to be there - typical KOA, sites close together etc. Weather was lousy - pouring rain - so we wanted something to do, and we found a gem! Not only is that the hometown of Neil Armstrong, there is a delightful space museum there that we really enjoyed visiting. And not far away (I think about 1/2 hour drive at most) was the Airstream factory, where we got a tour. Opening date for this CG is given in the 2014 KOA book as March 15th, but the winter being what it has, you may want to check ahead.
We have also stayed at the Dayton KOA, probably 20 years ago by now. Much of it seemed to have nice space between sites, and lots of open area with lawn, ponds, etc. Granted, we were in a popup then; I don't know if the sites for bigger rigs were as pleasant as ours. Opening date given as April 1st.
