Used this site for the last 5 or so years and will be on there again this year.
The site has showers and loos in 3 or 4 locations. Avoid the lake area, it looks nice camping pond side so to speak, but in heavy rain will flood and the midges are hell.
Good atmosphere on site and an easy walk to Tetre Rouge and the Village.
The other big plus is when you want to go to the hypermarket, you don't get stuck in the traffic that builds up on the Mulsanne or round by the main entrace in the days before the race.