Strictly, you would have to register your aircraft in France, and obtain a permit to fly there.
I know that they only allow the standard kits, and not the quick-build kits for the RVs in France. I'm not sure of the position for importing homebuilts.
There are several RVs flying in France, and some builders/owners are on the Yahoo "RVSQN" e-mail list
rvsqn. That may be a good source of contact.
You may also be interested to make contact with
vansclubdefrance/