Hi TX and welcome to the forum. We used to go camping along the coast as often as possible when we lived in the McAllen area. Been to Mustang Island SP and Padre Island NS a number of times -- the latter being one of our favorite places to camp. In fact, the picture to the left is that of our first trip to PINS.
But, alas, we moved to North Texas a year ago and Gulf coast camping is no longer convenient for us.
The upside is that we are now within as little as 'minutes' away from the nearest SP or COE park...which makes weekend getaways much easier.