I think you did a pretty darn good job with your Southern American accent. Most people put WAY too much of a drawl on theirs, but yours was quite refreshing. I'd recommend you maybe slow it down just a bit, without putting as much of a pause in between the words, as weird as that advice might sound. This is probably better advice for a more eastern Southern American accent, since I am from Mississippi. Great job overall, though I'm a much worse judge of the other accents, so take that with as much salt as you want.