If you're okay with fiction, in Barbara Hambly's
Benjamin January series of historical detective novels, the eponymous character is an ex-slave freed in childhood and trained as a surgeon and musician, who regularly goes "undercover" on plantations and such to solve cases in antebellum New Orleans.
It's a very good series which has garnered a fair amount of praise, not to mention being one of my personal favourites, and there's plenty of character perspectives on slavery, freedom, and the shifting ground between both as it relates to societal conventions and constraints of the time, as well as on universal principles.
Also, if you'd prefer to read stuff in e-book format (only the 4th to 8th available, but
Die Upon a Kiss is a pretty decent place to start and each book is standalone as far as the main story goes, though they pick up on personal developments in previous books), these are published by Random House, so there's no Agency pricing involved and you'll be able to use discount coupons if your usual store offers them.