Being close to the ocean you will need to wash your rig with fresh water to reduce rust. I give mine a good under wash anytime I drive close to the ocean even if I do not camp on the beach.
My first beach camping (Point Mugu, CA) trip produced more rust on my rig in one week than I normally get here in NM in 5 years. BTW I was in Corpus Christi the year they had 4-5 inches of snow on Christmas :S, so watch the weather forecast as you go along.
I too will endorse the state parks from TX to FL. We did not have any trouble getting sites but we traveled in Nov not Dec-Jan.