Mustang Island State Park near Corpus Christi TX has 50Amp/W spots about 100 yards from the beach - or your can take your rig onto a 1.5 mile stretch of beach and dry camp. Check with the rangers first, and drive the beach in a small vehicle before going out there.
In October, I saw a 35 ft DP about 1 mile down the beach.
Padre Island National Seashore - a bit further south has 5 miles of on the beach dry camping available for non-4x4 vehicles - 60 miles for the 4x4 crowd. There is also a dry campground with toilets and tables right off the beach before the pavement ends.