See:
Camping-cars: ce qui est permis ou interdit - Voiture - Notre Temps
QUOTE:
• Is there a speed limit?
No. If the camper weighs less than 3.5 tonnes , there is no specific speed limit for this type of vehicle in the Highway Code: they are subject to the same rules of conduct and the same speed limits. than other vehicles in this category. However, plan for greater safety distances and watch out for the wind!
Yes. If your vehicle weighs more than 3.5 tonnes without a trailer , you must respect the following limitations: 110 km / h on the highway; 100 km / h on two-lane highways separated by a median; 80 km / h on other roads; 50 km / h in built-up areas. You are not allowed to drive on the left-most part of a road with more than two lanes if your vehicle is over 7 meters long or is a heavy vehicle.
And also:
• Can I get a car on my motorhome?
No , according to the Highway Code, only a trailer is allowed to be hitched to a motor vehicle. Except for the breakdown service, it is forbidden to drive in a rolling set consisting of a motorhome and a car. It must be placed on a trailer (approved car carrier) to be towed behind a camper.
... and I can attach bikes?
Yes , all over Europe, except in Portugal where it is forbidden to carry bicycles in the back of your vehicle.
Code de la route. | Legifrance