2019 - You're planning ahead!

As Walkabout says France is stuffed full of municipal (= run by the town as opposed to private companies) campsites. I've stayed in a few of them over the years on the route down to the Alps that I outlined.

Starting in Reims, go over the Montagne de Reims (a slightly hilly area) on the D951. Campsite 1 is the municipal site at Epernay - on the banks of the Marne river. Stick with the 951 south to Sézanne and then the D373 towards Troyes.
I've never camped in Troyes (only used hotels) but about 10 miles east is a lake /park area, Foret d'Orient. There's a lot of campsites there but they're mainly commercial sites (= quite expensive) as the whole area is a kind of family holiday zone. I've stayed in 2 sites (can't remember the names) there over the years and regretted it each time.

From Troyes head south on the D671 towards Chatillon sur Seine and about 10 miles later turn right onto the D971 towards Dijon. There's municipal sites at Chatillon (not stayed there) and, further south, at St Seine l'Abbaye (v quiet small village). There's a municipal site in Dijon close to the lake and near the centre of the city that's one of my favourites but it's v popular and fills up early each day.

From Dijon you can either head south on the D974 (through the wine growing area) to Chalon sur Saone (a busy road and not that much fun) or, from Dijon, go slightly south east on the D996 towards Seurre and via a bit of twisting and turning to Louhans. There's a nice municipal site there behind the sports stadium and backing onto the river. It cost me €4 last time I was there. No food though and Louhans closes early.

From Louhans take the 996 towards Bourg en Bresse (through chicken land) and out south on the D1075. That'll take you all the way to Grenoble along (for part of the way) the valley of the Rhone river. There's quite a few sites along the river section from small municipal ones to huge Butlins type places (Vallée Bleue) but they're all too close to home for me.

Take the A48 (urban motorway) for a few miles through Grenoble (it's a nightmare otherwise) and leave at junction 8, the N85 to Vizille. Then take the D1091 along the Romanche valley to Briancon. There are a cluster of campsites near Bourg de Oisans (3 posh ones at the base of the hill to Alpe D'Huez). There was a landslide at the Lac du Chambon a few years ago that blocked the road and still (as of Jan when I was last down there) wasn't completely fixed but EU money should have done it by next year. Briancon is on the Italian border if that's where you're headed. Reims to Briancon is about 500 miles.

Oh, and ps. There are an increasing no of speed cameras on the route I outlined. If you see a sign that looks like a speed camera there will be one in the next mile or two. They're grey boxes at ground level as opposed to our yellow boxes on a pole.