Saint Etienne is a small working class city in France.
Get on the last traffic circle on the "rue de la Montat" before the motorway. There is way enough place for the cars to stop an they are not so fast
The best is to hitch North to Givors and try to get dropped on a petrol station/toll on the A7.
West toward Clermont-Ferrand
Echangeur de la Terrasse
Go to train/tram/bus stop "Passerelle" (T1 and 2). From there you can see a pedestrian bridge going over the train tracks. Take it. You'll land right next to the highway, but the wrong side. Turn right and walk until the big crossroad. There you can go under the highway and hitch from the onramp.
There is light at night.
Get off the tram at "Bellevue" (lines 4 and 5) and walk up the "rue Robespierre" (you'll pass hover the motorway) to get at the Vélocio traffic circle. Hitch where the sign shows "Bourg-Argental, Annonay".
It's working quite well and the road is beautiful. You'll be slower than on the highway but you'll meet more people since they'll take you for short rides
To go to Grenoble, do not go to Annonay but take the road passing it north crossing the motorway around Chanas and keep east across Beaurepaire.