Yup, we had our crisis in January as apparently no more camping tickets available. We got sorted, but just to confirm ACO confusion and French logic reigns, I just noticed that the official ACO Billetterie now has
Vert - Houx Annexe & Karting Nord
Rouge - Expo
Bleu - Nord & Sud
Jaune - Arnage, Mulsanne, Beausejour, Dairon and Pincenardier
Available
here. (If you are an ACO member or want parking/tribune tickets you can hopefully find your own way around.)