I finally got back to researching this and took a look at the hardcopy volumes of Roster of Confederate Soldiers, 1861-1865, and there is a William P. Proudfit shown in the 5th (McKenzie's) Tennessee Cav. Regt.

A little research shows this regiment formed from the 13th Battalion Tenn. Cav., which in turn, had formed from the 1st (Roger's) Tenn. Cav. Regt. All of this occurred in less that a one year time span. The 1st was organized in Jan. 1862, and the 5th was organized in Dec. 1862.