daferg, I have also made modifications to the USA oob. I originally was also inspired by the SBCT units and formations. This was way back when the first real BCT was still in the test phase. I saw it was going to be organized differently so I tried to come up with the best solution. Take a look at my mod in the mod section or here:
http://forum.shrapnelgames.com/showthread.php?t=49329. I have also reworked many different formations and new ones also. Even from new HBCT and IBCT formations. Hope this helps you see what is possible in game and maybe inspire what you are looking to do.
USA 1980-2020 Mod
http://forum.shrapnelgames.com/showthread.php?t=49329
Gooseman2448