Another bio extends the length of time Cavan Wyatt lived in Centralia postwar to 1875. Wedding record refers to him as John c. Wyatt so that name was also used. Kate Garrard was too young to have been wartime sweetheart. Looks like marriage was 1875. Her father was James Garrard, son of former governor of Kentucky.
And James Garrard actually owned the battle of Centralia site after the war. Garrards were very wealthy and it appears family money allowed Cavan Wyatt to buy into and become a major player in St. Jo mercantile business.