We will be in the South of France in October and just assume most sites will be closed. We plan to stay a few days at Carcassonne though and the sites open till end Oct. There is an aire next to it which is all year but quite expensive so for the small difference we use the site.
ACSI book or site will give the opening times of their listed sites.
Can you get hold of an old ACSI book? When I joined MH Fun Chas17 very kindly sent me his old one. I e been through it cover to cover and marked up all the sites that will be open for our October fortnight. We’ll follow the weather ... if I get a chance over the weekend I could send you a list of all ones in that area ..