Darrel,
If you are travelling around the 8th, or possibly the 15th, the roads should be pretty quiet. Especially as it will take you a couple of days at least to get south. Yes, they are even better on a Sunday because many of the heavy trucks are off the road (Oh, to have the same here).
Curious to know the site you are looking at, only asking in case you have found something better than we did. We stayed latterly at a Yelloh site beside Agde. Very good and big (400 places) and of course entertainment EVERY night. I did enjoy the ABBA lookalikes, but the kareoke left both of us cringing and running for cover.