Just taking a wild guess here but I would say there are at least 20 RV parks in the Rockport area which is about 30 miles north of Corpus.
In Rockport I've stayed at Rockport 35 now called Wilderness Oaks, Sand Dollar and currently at Salt Water Flats and over in Corpus I've stayed at Colonial Del Ray.
Each park has its advantages and disadvantages. If I were you I would come down a couple of days early and ride around and check them all out.
I've been coming to the Rockport/Corpus area since 2014 and like LynnandCarol said this has been the coldest winter by far, yet we only went below 32 for a couple of hours and no more than 3 days. I've also stayed in the Tampa area and while they certainly beat us this year temperature wise, last year we were warming than them on most days.