KOA Campgrounds
(956) 761- 5665
1 Padre Blvd. South Padre Island, Texas
http://koa.com/campgrounds/south-padre

Other camping options:

Isla Blanca State Park- Located on the Southernmost Tip of SPI. Not open to public tent camping. Not available for over night RV camping. Some possible lodging options. Offices close at 5:00pm.
Cameron County Parks System.

Andy Bowie State Park- Located on the North End of the Island. Not open to public tent camping. Available for overnight RV Camping. Offices close at 5:00pm. Cameron County Parks System.

Sea Ranch Marina- Located behind the Sea Ranch Restaurant on the South End of the Island. Great place for tent camping. Camping is $7.00/night. Offices close at 5:00pm. Public Showers and Restrooms Available.

North of Beach Access 6- Just passed the 6th Access of the North end of the Island, beach camping is allowed. You are also allowed to drive on the beach here, but 4x4 is strongly recommended. Camp fires are also allowed here, but as always, please be mindful about putting them out properly. (Please do not burry hot coals in the sand).  Please remember to take all of your trash with you and leave only footprints!