For RVs, the best spots are the trailer parks at Paraíso Costa Alegre, (Km 72, Carretera 200, Barra de Navidad a Puerto Vallarta, tel. 315/333-9778 or 315/333-9777, www.paraisocostalegre.com.mx [1]) the Hotel, Bungalows and Trailer Park Playa Dorada, (Perula, Km 76, Carretera 200 Melaque–Puerto Vallarta, tel. 315/333-9710, fax 315/333-9709, www.playa-dorada.com.mx [2]) and Red Snapper Restaurant and RV Park (P.O. Box 42, Melaque, Jalisco 48980, tel. 315/333-9784, redsnapper [at] hotmail [dot] com).
If you can walk in, you can probably set up a tent anywhere along the bay you like. One of the best places would be the grassy dune along pristine Playa Rosada a few hundred yards north of the Centro Vacacional Chamela Sección 47 (Km 66). Water is available from the manager (offer to pay) at the Centro Vacacional.
Playa Negrita, the pristine little sand crescent that marks the southern end of Chamela Bay [3], offers still another picnic or camping possibility. Get there by following the dirt road angling downhill from the highway at the south end of the bridge between Km 63 and Km 64. Turn left at the Chamela village stores beneath the bridge, continue about two miles, bearing left to the end of the road, where a restaurant palapa stands at beachside.
This is the southernmost of two islet-protected coves flanking the low Punta Negro headland. With clear, tranquil waters and golden-sand beaches, both coves are great for fishing from the rocks, snorkeling, sailboarding, and swimming. The gorgeous south-end beach, Playa Negrita, is offered as a campground, with plenty of room for tenting and RV parking; a friendly caretaker sometimes collects about $2.50 per day per car. Weekends and holidays the restaurant provides drinks and seafood lunches and dinners.
Links:
[1] http://www.paraisocostalegre.com.mx
[2] http://www.playa-dorada.com.mx
[3] http://www.moon.com/destinations/puerto-vallarta/the-jalisco-coast/road-trip-barra-de-navidad/chamela-bay