Are you talking about North or South Padre Island? There is a big difference. The camping at the North Padre Island National Park HQ is very nice. They have Electric and Water and a dump station. It is small so you need to call for reservations. There are has day use for the public but the RV park area is physically isolated from that but since the beach is open to any park visitors you could see some bach traffic, especially on weekends and holidays.
Jim & Gayle