Convert USBs to dynamic disks with the disk manager. Convert to RAID 5 or 6 in WinServ 2008 or 2012 (anyone know a way to force Windows 7, 8, or 10 to software-manage fancier RAID configs?).

Poof - you now effectively need m of n USB disks to access your coins with minimal effort on your part (do you need to match the USB ports? Beats me!). You're welcome (I have no idea what happens if you start writing some updated wallets or keys to some USB sticks and not others, and then try to write to those others later without rebuilding). The Internet suggests you can also natively do this in some linux distros.