Towing to the Med.
Hi, i have travelled this route 5 previous summers towing 1.5 tons of twinaxle caravan, have since sold and bought a 5.35m rib though!.
As suggested the roads are very good, with service station/ rest areas every 30-50km, with excellent facilities, however don't leave the outfit unattended, and don't sleep in the car!, there are plenty of cheap hotels on route, however from exprience over Christmas book ahead.
The tolls from memory will cost you about £150 return from the South of France, for the outfit, as commented you certainly pay for the roads, however diesel is cheaper and petrol very slightly also. If you travel mid-week you may save on the tolls, paying for the car only, check out their web sites for info.
Last of all allow yourself 2 days driving, leaving Calais at around 10.00am will comfortably put you around Macon for the overnight stop for around 6.00pm at a steady 60mph, also on the way back look out for the mobile speed camera outside of Calais on the last motorway leg, British drivers running late for their ferries are easy pickings!. Spotted this last July and at Christmas driving back from the Alps, they must be camped there all year.!!.