separate windows drive on mac pro without bootcamp

I have a 2009 Mac Pro with PCIE card with two SSDs in Raid0 as the OSX boot drive (El Capitan).

Since OSX can't install bootcamp on an "external" drive, I wanted to see if I can just move my Windows 10 SSD over from my PC and install in the MP and run with it.

So I installed rEFInd bootloader and then installed my windows SSD (after running sysprep on it...

separate windows drive on mac pro without bootcamp