A request

As you know, I am trying to work on a book on subsidiarity.

I have found what may be its foundation in the advice given to Moses by his father-in-law Jethro:

"...provide out of all the people able men, such as fear God, in whom there is truth, and that hate avarice, and appoint of them rulers of thousands, and of hundreds, and of fifties, and of tens, who may judge the people at all times: and when any great matter soever shall fall out, let them refer it to thee, and let them judge the lesser matters only..." (Exodus 13:21-22)

Clearly, this is very hierarchical, and very relevant to computer-science (if you know what we mean by a "tree" you will understand!)

Now here is the request. Earlier in Exodus (12:37) we learn that there are 600,000 MEN who leave Egypt.

So... Does anyone know - and can give a reference to - a commentator who shows HOW Moses arranged his hierarchy of judges?

For, if one divides up 600,000 according to the rules, we get:

600,000 over 10 is 60,000 "rulers of tens"
600,000 over 50 is 12,000 "rulers of fifties"
600,000 over 100 is 6,000 "rulers of hundreds"
600,000 over 1000 is 600 "rulers of thousands"

Was there then another layer of assistants - isnt't there something about 72 elders?

Or did Moses have 600 "rulers of thousands" reporting to him?

If you can help with a reference, I will be quite grateful. (Speculation is nice, but not as helpful; I'd like to hear what the Church Fathers or the great saints said - or at least someone trained in Mosaic commentary...)