In search of Padre Island--North or South?

We're headed south, to find Padre Island, on the Texas Coast. First, we're going through Corpus Christi, and out to Mustang Island, which is just north of Padre Island National Park.
Mustang Island has a state park, where we're headed for the night. We hope to stay on the beach.

No luck camping on the beach. The office ranger really discouraged us; said the sand is very soft and the beach is very narrow, and we wouldn't be able to turn around.
So we decided to camp in the state campground and take a Jeep ride out to the beach.

We got to the beach and discovered people driving in cars and camping in tents, all over the place.
And they provide trash barrels, port-a-potties, and showers all along the beach! The beach was as wide as what we're used to at home, much less soft, fewer rocks, and very flat. We think they just didn't want to deal with RV's on the beach.