I'm relatively sure that this doesn't exist. Material for baritone ukulele is kind of sparse, and the instruction books I have seen or know about are all for right-handed players. The recommendation given in one of them (which I have seen in guitar books also) is that left-handed players play right-handed. I don't know how feasible this advice is, but both hands have challenging tasks when playing a stringed instrument, and I think it may actually be an advantage to be able to fret with the dominant hand.