So far, I've only seen Wilderness Camp at
Hill Country State Natural Area. I got a good look at the campsite during my
solo trip to HCSNA in May (see link; includes a photo & details).
Summary: "Wilderness" is a nice, varied campsite -- dense oak trees with a picnic table and tent-able area underneath (similar to the walk-in campsites along West Verde Creek), and a small meadow and rise across from the site where a hay shelter (for horses) and large fire ring are located. Tall, forested bluff rises behind the site and a handful of trails run near or begin at its "doorstep".
The
Hill Country State Natural Area Partners (HC-SNAP) club may have more info for ya -- great bunch o' folks who spend a lot more time at the park than is rightly fair! (that's sarcasm, actually; everyone's welcome to join, from hikers to mountain bikers and equestrians. Right now, they're mostly equestrian folk and would welcome some more hiking representation!)
Someone else here had a recommendation on primitive sites at Lost Maples.