Dag gummit....
Jim McGhee you scally-wag, you scoped this out years ago... Lo and behold here is a listing in Co B Clark Twsp Cole County Southern Guards : Named just as Ms Whittle described:
Crabtree, L. P., 1st Lieutenant, B Troop, 1st Cavalry - SG
http://www.colecohistsoc.org/civilwar4.html
So I concede its not JW Crabtree of Arkansas. But I sure learned a lot about HIM.
John R