Another great TL that I almost missed... as the discusion ended in August, I assume it's over? A small linguistic nitpick. You describe the Nok area languages as if they would look more or less the same like today - tonal languages with open syllables, etc. But tones very frequently go back to lost segments, especially consonantal segments. For example, look at reconstructions of Old Chinese; the time difference between Old and Modern Chinese would also be about the time distance between your Nok and the modern languages of the area. So it's very likely that the ancestor languages would have many more consonant clusters than its descendants and no tones; they would have looked very different. Of course, we don't know 100%, and I don't expect you to change things this late, but I thought you might be interested.