We toured pretty much the whole length of Padre Island last winter. There are miles of beach open for boondocking if you are so inclined. Most places require a "parking fee", but they are minimal - usually like $12/year. There are also RV Parks scattered up and down the coast - obviously in the more developed areas. The closest to Corpus is Port Aransas on Mustang Island, and there are several RV Parks there as well as beach access. Most of the RV's we saw on the beach were truck campers on 4WD trucks, or 4WD trucks with smaller, lighter trailers.
