cache

All, I have an oddity that hopefully someone has some ideas.

My infrastructure does not support traditional IP structures.
When we set up Apple Server to do Caching it instantly disables and errors out that we are using a public network. Which we are not, we just (as I said) don't use the traditional 10.*.* approach.

We need to upgrade multiple devices in multiple locations and don't / can't tie up the bandwidth needed to do them all over the air.
Here is an example:
One location may have 300 iPads.
iOS 8 is going to come in ~1.7 gb.
You don't have to be a network genius to see that 510gb of data, is going to drop traffic to a crawl!
Especially when other traffic gets the majority of the bandwidth and these device scavenge for what they get.

Has anyone tackled this, if so... please elaborate.
Are there other offerings Casper or SCCM come to mind in my quandry.

Any and all assistance is a boon at this point,
Thanks!