I can't speak directly to the campground that you are inquiring about, but I can speak to allergies in Texas. The area I live in (close to San Antonio) is called one of the worst for the allergic person (like me). There is some sort of bad allergen in the air every season. My allergist call it a "year rounder" area. Of course this may not apply as much to the valley area, but my guess would be the environment will be similar.
But if your wife's allergies do not include the pollens in this area she could be fine.
, Chief Executive Navigator
33Ft. Crossroads Sunset Reserve TT