I was incorrect on the NPS listings.

The NPS Soldiers and Sailors System does indeed list the Frontier Regiment, Texas Cavalry (46th Regiment Cavalry).The listing only consists of Co.A and B of Capt. Fossett's battalion at Camp Colorado after the other four companies were removed to the coast.

Also listed is McCord's Frontier Cavalry, Texas Cavalry.It lists 1258 men.

However, no Isenhour or Eisenhower is listed in either group. I guess that was a dead end.