gap165, I don't think you have to disconnect anything at all to install a second operating system. Upon installation of Windows 7, press the usual sequence booter (most likely F4), boot into Windows environment and then continue on from there by choosing which ssd or hard drive you'd like to install Windows 7 🙂
I've done that a while ago, when I had Vista and then decided to experiment a little, so I installed Windows 7 on a seperate hard drive. After post sequence, I had a screen where I can choose the operating system to start with 🙂 That was a couple years ago and everything else only could of evolved to a better perspective until now. If my suggestion doesn't work, your's seem's like a pretty good idea however I don't know about disconnecting the primary Windows ssd and then continueing on installing the other Windows version. Be sure to back-up all of your necessary data before you proceed 🙂