try these websites they have a shedload of infos not only france but pretty much of europe
a nice scottish couple(Danny and Sandy - ah those summer nights) we met told us they use to use french passion
but with a little research they did it all by these types of websites using free wifi at maccy d's
if you google aires de campingcar you get loads of places to stay both cheap and free
in french but with a little playing around and using translator you get a lot of info
http://www.campingcar-infos.com/index1.htm
http://www.i-campingcar.fr/accueil.htm
i-campingcar you can download a google earth location map and a PDF list for france (telechargement is french for download) just register and work it out -its free
there are a number of these sites the great thing about these 2 is they are free and useful for planning a trip
we have used the stop at Cleres just north of Rouen - free to park and you can buy a 'jeton' from the local shop for 6 hours of electricity nice village with 2 or 3 restos a shop and bakers and a zoo (didnt visit too busy enjoying wine)
dont know if this helps but we liked the town and not far off autoroute certainly worth it for a freebee stop
will be going to france this summer but in NI for easter may see you around -the caravanning and camping club uk have a rally in portrush over easter probably be there
happy aires
FRENCHMICK