It is very possible as there are a lot of municipal campsites which just operate in France during the summer (6ish) weeks, it feels like most villages have one nearby. As they are not all singing and dancing sites they tend to be a lot cheaper. I would avoid the coast areas where it will be absolutely packed as that is were most French (sorry very broad generalisation) tend to head. We were in the alps last summer during the main French holidays and it never got busy but there was lots to do and none of the sites seemed busy.
no, you're not mad. We have done this loads of times. We use the Green Michelin camping and caravaning book, you can get it over here but it's in French so you need to understand a few key words. It gives loads of sites but also the Municipal ones which are basically the ones run by local towns and villages. Have satyed on some lovely little sites with just showers, washing areas, maybe a sall playground but no cafe, bar or pool. Usually have French, Dutch families but few English and no Euro camp type arrangements. In the past they have been very reasonable. Some do get full but many are relatively quiet.
Hello my husband and I are both teachers with two young boys. We'd love to set off for France at the end of the summer term (5 weeks off) and just see where our mood/weather/campsite takes us. I don't want to pre book campsites as we want the freedom. Are we mad?! We are more than happy to stay at quiet ones with limited facilities just the sun (hopefully). Any advice would be gratefully received. Thank you :-)