Hi Ron,
I have the same make and model van as you and went to France last year without problem, stayed on a total of three different sites.
I have seen some French sites stating they will not accept carvans over a certain length, I believe this is more to do with access issues and affects both single and twin axle vans. I have also seen one photograph posted on a forum indicating twin axles were banned from at least one site.
Prior to owning the Barcelona I had a twin axle Wyoming which I also took to France without problem for three or four years. I would advise doing your homework, drawing up a list of sites you might want to visit and either check out their websites or phone them direct and ask if there are any restrictions. Are you planning on booking or just going where your fancy takes you? I usually book, either direct with the site or through a third party such as Caravan Club or Select Sites (sometimes a combination). The Caravan Club and Select Sites literature indicates any length restrictions, whether using them or booking direct I make a point of saying it is a twin axle van. Never had a problem with taking a twin axle to France, just be aware that there may be length restrictions on some sites.
If you have any particular sites in mind if you post their names someone might have actually visited and will be able to give you more info. I would recommend La Garangeoire in the Vendee area as worth consideration
http://www.camping-la-garangeoire.com/en/index_en.htm
Robert