Just a question, how many levels of belt rankings are truly necessary? It seems to me that the constant expansion of rank structures has more to do with "oneupmanship" than with organization. Arent some of these Bujinkan orgs up to some extreme levels now? You have student ranks, then instructors, than someone who administers multiple instructors. I would think that instructors would need a basic, intermediate, advanced level. And the person overseeing multiple instructors would only need one rank. Over them all could be the head of the system.
I like your system, but remember that the 10 degrees of black belt in use now is still essentially the same as the original system developed for Judo by Jigaro Kano. It hasn't crept in over the years--it was always there. We have the overly organized Japanese mindset to blame! It's been a very successful meme, though.