USCT research I've done has been on lives of individual soldiers. Some served with most of the units listed in the request for location. This is an excerpt from the history of a Camden County soldier, Judge Torbert: The 67th Regiment moved from Benton Barracks, Missouri, to Port Hudson, Louisiana, arriving March 19, 1864, and was on duty there until June. Judge Torbert was promoted to Corporal on May 1. A detachment of the Regiment saw action at Mt. Pleasant Landing, La., May 15, 1864. The Regiment moved to Morganza, La., and was on duty there until June, 1865. Judge Torbert was promoted to Sergeant on July 1, 1864. Expedition from Morganza to Bayou Sara September 6-7, 1864. He was reduced to ranks on October 1, 1864, for disobedience of orders and habitual misconduct.
Best guess is the companies in the 67th Regiment were based out of Morganza, La. during the months in question with some expeditions nearby. You mentioned the conditions around Benton Barracks - if possible, it was even worse in La. So bad that white officers complained to their superiors about the USCT conditions.
If this is helpful I'll go through and try to tag the location of some of the other soldiers for you. It'll take some time, so let me know if this is information you already have.