Unfortunately, we do have any Regulations from 1860-1865 before The Citadel closed down after the end of the Civil War. Based on the photographs below, it appears that Citadel uniforms did not undergo any major alterations during this time.
During the Civil War, the cost of goods became extraordinary, especially in the South. By 1862, all Pay Cadets were required to furnish parts of their wardrobe and pay $400 tuition. From the 1862 Board of Visitor Meeting Minutes:
"Resolved, That hereafter during the existence of the present high prices, pay cadets in the South Carolina Military Academy be required to furnish their own under clothing, including shirts, drawers and socks; also their shoes, combs and brushes, and pay annually four hundred dollars, viz: one hundred dollars per quarter in advance."
By 1864, the cost of tuition had risen to $1200 per Pay Cadet, which was a factor in the decision to close the school. From the 1864 Board of Visitor Meeting Minutes:
"The Board regret to state that, that source of supplies is now cut off and both subsistence & clothing will have to be purchased at the enormous prices asked in the open market. The Board has, therefore, increased the amount to be paid by Pay Cadets to twelve hundred dollars for the year, and they ask of your honorable body a corresponding increase in the appropriation for the Academy, for the pay of the Officers and support of the State Cadets."