My wife's great, great grandfather was on the filed that day too, not far from where this marker is located. His regiment, the 3rd North Carolina, was badly mauled. He was wounded himself and sent to a hospital in Staunton, Va., for treatment.
You seem to be lucky that there has been a lot written about the 5th Texas. I've been researching an ancestor who served in a unit that wasn't famous, and seemed to be something of a 'hard luck' brigade. So I am piecing together material here and there to try and get the big picture. I've discovered some new material by contacting the the chapter of Sons of Confederate Veterans that is linked to the unit, so that might be a productive avenue for you as well.