I can recommend Camping Moto Rendezvous
http://www.camping-rendezvous-moto.com/ in the south of France. Owned and run by a Dutch couple, it's as laid back as you'd expect. It has a deserved reputation as the partyest of the French bike-only campsites, so pitch as far from the bar as possible if you value sleep. You're greeted with a beer when you arrive. All beer and food is priced on a points system and goes onto a tab, so be warned - it's easy to build up a large tab
and payment is strictly cash-only.
Turn off the A74 at Lodeve and head towards Lunas along a back road that alternates between fast sweepers and first gear hairpins. The whole area is Buell heaven - criss-crossed by twisty roads - and the A74 north of Lunas has to be the greatest stretch of motorway in Europe, twisting endlessly down one side of a gorge. Heading south (downhill), it's thrilling and scary in a "Oh f*ck, the front end's going to wash out" way, but you
will want to turn around and go back up again.
North of Lodeve is the Millau viaduct, which is as stunning as the pictures suggest.
The Med is an easy blast to the south. Also in the area are the Rocquefort cheese caves - well worth a visit. We had an unintentionally funny guided tour of one of the caves, complete with diorama showing how the caves were formed - "You see, Mr Bond, you are too late to stop me. The cheeses you see here are all plastic replicas - the real cheeses have already been distributed around the globe, and soon I, Count Rocquefort, will rule over the dinner parties of the bourgeoisie!"