Seems to me that you are discussing IP Number allocation here, not core network design which has a lot more associated with it than just what IP ranges you are going to allocate to where.

There are a number of other things that will need consideration.

Who owns the network ?
Who manages the network ?
Who enforces management ?
How ?
What if a client decides they dont want to listen to you ?

and not forgetting such things as

What is the topology of the network ?
- how does it all interact ?

What is your target market ?
Where do you want to be in 2/3/4 years time ?

Address allocation should be quite far down the priority list, tho yes - it is good to keep track of what is currently in use - it should also be allocated with a mind that should renumbering need to occur it can happen quite quickly and easily.