Mustang Island, the city park at Port Aransas or the state park, are what first come to mind, but neither has "ocean view" from a campsite. At the city park you are sort of on the inlet and in the state park, over the first row of dunes from the actual shore.
Seeing the ocean and not being in the sand are inconsistent with the geomorphology of the Texas Gulf Coast barrier islands. They are not stable, the sand is still moving any place where you can see the Gulf water.
Galveston Island Beach state park gets you really close to the beach, but you will still be parking your RV well away from the high water line.