I have a different take on Padre Island than the other posters here. We were there last year and camped about 10 miles down on North Padre. South Padre if for teens, drugs, and partying. North Padre is for fishing and drinking.
I have to say it was the worst camping experience we have had to date. I will NEVER return. Wind, masses of seaweed, oil laden slimy goop covering the truck and camper. I still have sand and salt blowing out of the vents whenever I turn on the blower. But the worst was the massive amount of trash all along the beach. They should call it Trash Island. Most of it was diapers, beer bottles, empty beer cartons and fishing line left by people who just don't care. We picked up enough trash just in our little camping spot to fill 4 large blazing orange trash bags that the beach patrol was supposed to pick up. They never did. They drove by them about 30 times though.
And if you are a non-resident be prepared to pay through the nose for a fishing license....oh and you have to give them your Social Security number too:R.
As far as driving on the beach is concerned, we didn't air down and had no problem. Although I did watch a girl bury her Tundra right next to our camper. She finally dug herself out.
Mike