(I know it's a few months old, but I'm surprised nobody has added any suggestions, hope this helps future holiday planners)
The capdagdenaturiste reddit, and the groups on fet have good info on the travel routes and costs in france. From Paris you get the SNCF train to Beziers station (about 5.5 hrs) and then a taxi to Cap (30 min).
If you're not set on flying in to Paris, it's easier and faster to fly to Barcelona then drive up - it's only a few hours drive on proper motorways and car hire is cheaper in Spain than France - you also get to sample the gorgeous nude beaches of Costa Brava along the way. If you go this route, then visit Carcassonne on the way back (just avoid Bastille Day, that sort of crowding was an experience)
Stay in the naturist village, it's cheaper outside in Agde - but then you have to travel in and out, it's a hassle. Just bite the bullet and stay in the village, you can stroll down to the beach, come back for a bite to eat then go to a foam party, have an afternoon nap and then go dinner, dancing club, people watching, and then people playing 
(look for airbnb in heliopolis - convenient for clubs and foam party, or cabins in rene oltra - they're nice, awesome air-con, and super convenient for the beach. Have stayed in the hotels, but they're bonkers expensive and not worth it IMO)
Le Glamour Foam party is a 'must try' in the afternoon. In the night, Melrose Bar for drinks, dancing, and then the crowd shifts to clubs like Tantra. Have heard good things about the Babylone pool party, and Histoire d'O - they look nice from the outside, but did Glamour and Tantra instead. (Tantra has plenty of staff keeping things safe/managed, unless it's your thing, I wouldn't hang out at the downstairs bar, just go straight upstairs to the upstairs bar and play area).
You'll be able to tell 'that area' of the beach, that crowd of people aren't milling about to check out the ice cream cart nearby 😉
