I now live in Louisiana and have the opportunity to visit the Vicksburg Battlefield occasionally (1-1/2 hours away!!). Interestingly, there are rifle pits in the trees surrounding the Second Texas Lunette that few people know of. Unfortunately, unless you wander into the brush, you'll never find them. One of my sons found an old plaque that a tree had grown around explaining the efforts of the Second Texas. Supposedly companies C and D were in those trenches forming an inverted "V" for the May 22 assault against the Lunette.
If you're not already aware, there is one recent book that narrates the efforts of the Second Texas. It's called From Shiloh to Vicksburg: The Second Texas Infantry, by Joseph E. Chance. It's well worth reading!! You can probably get a used copy at amazon.com for only a few dollars.
Wes