You can park at the Torre Guaceto reserve and stay overnight if desired.
Tickets cost 8 euros until 8pm. Free shuttle trains run every 10 minutes to take you to the beach in the reserve, but they stop running at 7pm, so it can get crowded in the evenings. It seems like you can stay overnight, but we didn't try it due to the nearby highway noise. The place is a bit dirty, though slightly cleaner than usual, even in a reserve.
Great stop-over spot! Campers can park for 8 euros until 8:00 PM (automatic payment machine), with the option to stay overnight as the parking barriers are lifted during the night. No facilities, but there is a shuttle service available to the Torre Guaceto nature reserve beach, where you can find a small bar with local products. Fantastic sea!