Oh that's perfect. Take Beltway 8 west (or I-69 if traffic is agreeable) down to I-10 then go get lunch in Fort Stockton then head home. 1,040ish miles so plenty of buffer. Nice high speed roads, and no reason to get off I-10 once you get on it. Just remember to get a receipt in San Antonio to prove you didn't go around it, and you'll be golden.
Then, if you enjoy IBA rides, take the same route but go all the way to El Paso and you'll be at 1500 miles for a
Bun Burner. Or you can really step up and do the
Ride Around Texas. You are practically on that route already. You've got a great home base for IBA riding!
Oh and don't forget to stay hydrated. West of San Antonio is literally a desert. I've ridden through there before and it can be rough. It's hot and dry and dehydration can sneak up on you in a very bad way. If you find yourself thinking about stopping to get a drink, DO IT! That's your body's way of telling you what it needs.