If you can manage a little French use www.autoroutes.fr and select that you are towing a caravan and that you don't want to use Autoroutes (Express as they call it.) Put a waypoint in that is away from Paris and you should be OK.
Suggestion: go Le Mans, Bourges, and then wherever in Burgundy. The municipal in Bourges is a good site about 10-15mins walk out of the city centre - a very pleasant and slightly up-market place but not big.
In Burgundy there is an acceptable municipal at Verdun-sur-le-Daubs. Sits on the island between the confluence of the Saone and the Daubs. Largish quiet site with much tree cover. Facilities are a bit aged but well clean and free. Electric is (from memory) 10A. Small but pleasant town centre is 5 mins walk. Best bit is that it is away from the holiday areas (about 10m SE of Beaune) but on good fast roads. Chalons-sur-Saone is a good centre and sits at the middle of Burgundy with Macon to the south and Beaune, Nuits St Georges and Dijon to the north.