I attended the Port Aransas Wooden Boat Festival Oct. 18, 2014. I planned to camp along the shore somewhere in Port Aransas. (no-hookups).
I found a few locations that looked good, but upon further inspection, found "No Camping" signs along the shore.
For $13 per night, I got a permit to camp on the beach at Magee Beach County Park.
After 3 nights of constant wind and pounding surf and humid 82 degrees all night long, I was ready to leave.
There were vehicles driving along the beach all night long.
I saw a few hardy tent campers with surf boards strapped on top of their trucks, but several of them left their tents to sleep in their vehicles.
Conclusion: No free camping in Port Aransas.