Here's what I've worked out:
Kerrville to Corpus Christi:
https://ridewithgps.com/routes/28796127An improved Borne to Leming (San Antonio north to south) route:
https://ridewithgps.com/routes/29008076Notes:
I put this together dreaming of Adventure Cycling one day offering a trans-USA, ocean-to-ocean short route, beginning at the pier in San Diego's Pacific Ocean and branching off the Southern Tier in Central Texas, running to the pier in Corpus Christi's Gulf of Mexico. I tried to stick to small, paved county roads out through the countryside, but just as in a few other parts of the country (and Adventure Cycling's own routes) there's a dearth of roads and in a few places I've routed down I-37, but, and it's a big but, in this part of Texas that means riding on the entirely separate access/feeder/frontage road that runs parallel to the Interstate highway rather than on the Interstate's shoulder.
There are city and state parks for camping and a collection of motels, but it's kind of a low population part of the country so plan ahead.
My route crosses the Corpus Christi Harbor Bridge. In 2020 a big new cable stay bridge will open with a barrier separated, latest-and-greatest compliant bicycle and pedestrian lane. Until then, the only crossing is the 1955 steel arch bridge. Bicycles are forbidden to use this bridge, but, and it's a big but, Corpus Christi city buses make the crossing on a frequent schedule and have bike racks.