Windows 7 Not Starting on Second Hard Drive

Here's some background:

I have a MacBook Pro (15-inch, Mid 2012). My intention is to run OSX on the primary hard drive (750GB Toshiba) and run Windows 7 on the hard drive in the optical bay (500GB Samsung). Through some trial and error and posts I have read on this site, I have determined that it is not possible to install Windows 7 on the secondary drive.

Keeping the latter in mind, I switched the drives, 750GB in optical bay, 500GB in primary bay, and Windows 7 installed and started fine. When I switched the drives back to where I actually wanted them, I got the 'No Bootable Device' error on the Bootcamp drive.

6 Months or so ago, I took the same steps and I was able to boot into both Windows 7 and OSX just fine.

On to my question:

Is this still possible to do or would I be better off adding a Bootcamp partition to my primary (750GB) drive and use the 500GB as exFAT that both Operating Systems can access?