This does not specifically address your query or ancestor Crockett Boone but I've seen many examples of the sobriquet or honorary title of Colonel applied to former privates who simply outlived their peers or were prominent in fraternal or business circles. There are also examples of common usage by those who had never served in the military.

One particulur example comes to mind of a Dallas resident who died in 1945 and had been proclaimed the oldest living Confederate Veteran. He was a General in the UVC but withdrew from a national election for unstated reasons. A detailed investigation strongly suggests he never served in the Confederacy and had adopted his role and war stories from others. Despite objections and compaints his status was never formally challenged.

Another is John Neely Bryan, the founder of Dallas. He was adressed as Colonel Bryan from the 1840's but his only service prior to then was a brief stint in the Seminole Wars where he did not see any action. It has been reported he was given the honoray title by various Indian tribes with whom he had lived and traded. He later served as a Lieutenant in the Dallas County Mounted Rangers and a private in Darnell's Cavalry Regiment. His son, John Neely Bryan Jr, was also known as Colonel Bryan after his father's death - he had served as a private in the 19th Texas Cavalry and was active with the UCV but not as an officer.

I found a number of articles in the Dallas Morning News archives re Colonel Crockett Boone, but as Vicky noted none explain the title or affiliation with the UCV. Most are in connection with his career as a newspaper editor-publisher-founder and even the notice of his death does not mention his military service.

This is not meant to impune Crockett Boone's service, reputation or memories, but rather for your to consider in trying to reconcile those to other evidence.

M C