Someone should tell Frankie Ford he doesn’t need to work this hard. On a Sunday evening in July, Ford’s big black Lincoln Town Car—the one with the “ooh-wee” personalized license plate—has brought him to the St. Bernard Cultural Center. The New Orleans Musicians Alumni Association is holding a benefit dance in a back ballroom. A succession of the organization’s members has been onstage all day, but Ford is the event’s marquee name.

When he agreed to donate his time for this show, he probab...