Have you tried Zilker Park?
Note: Zilker is a pulic park and all the normal precautions and etiquette applying to the non-flying public should apply. I expect
like most parks, the crowds will start thinning out as the weather gets colder and the Fall winds start to settle in.
You might also contact Tye at World Wind Kites even though power kites aren't their primary focus to see if there are other local flying fields.
ATB,
Sam
"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King