I am 5'8" too but I don't go longer than 14 1/2 inches... more or less. I can order a 16 inch unit .. but after I
doctor on it .. it becomes shorter for sure. The CVs are quite generous in their lengths.
IMO a shorter length is more realistic. When people talk about or stare at person A or B .. they can tell it's a wig or weave... but I am standing right there next to them and they can't tell what's on my head. I don't say anything .. at all - I hate gossip anyway. :(
Works like a charm but read carefully or watch the videos carefully and GO SLOW. Don't rush it .. until you get the process down. :)