You asked about Thomas' Alabama Cavalry Regiment. Here are some of my notes on that organization:

On April 26, 1864, General Leonidas Polk ordered ten companies on duty with the Conscript Bureau to assemble at Montgomery, Alabama. These were expected to form a cavalry regiment under command of Bryan M. Thomas of General Withers's staff. However, companies commanded by Captains Chisolm, Love, McDonald, Moses and Smith failed to report, and shortly after May 18, 1864, organization of Thomas's Alabama Cavalry Regiment was abandoned. Captain Lewis was appointed Major and assigned to command the remaining five companies. Also called Harrell's Battalion after the death of Major Lewis, officers and men mustered at Blue Mountain, Alabama, June 10, 1864.

As you can see, the surviving organization was called Lewis' (later Harrell's) Battalion.

With regard to other mounted reserves during Wilson's Raid, the two commands that fought from Montevallo to Selma were Hardie's and Barbiere's. The ADAH has a news clipping on file from the Greensboro Beacon which lists members of Hardie's Battalion who were captured at Selma on April 2nd.

With regard to the 64th and 65th Alabama, if these organizations really existed, one would expect that a substantial number of paroles would exist which reference these commands instead of the handful that appear on record. We can only speculate that these were proposed organizations of existing units, but what they were and how they were to be assembled is anyone's guess.