Driving to Marseille

Has anyone driven to Marseille from Calais, i am looking for some advice on the journey.
My daughter has been selected to ride for England in the european championships in Marseille in july, we will be travelling with my RV and a horse lorry with 2 ponies on board. We know that it is 1075km to our destination and will need to make a couple of stops on the way to rest the ponies, we have googled the route and have decided to allow approx 20 hours driving time. We are intending to stop at the lorry rest laybyes and corral the ponies for a few hours, will we be allowed to do this, we know that most of them have very large grassed areas as we have travelled in France before and did not have any problems with stopping and allowing the ponies to stretch thier legs for an hour or two. If we need to we will make an overnite stop at a farm if we can find one that will allow us with the ponies, advice will be greatefully appreciated on any stopping areas also on driving route
Regards billyfreda
ps, if interested my daughter rides in the mounted games go onto the MGAGB website for information