I cloned my PC's SSD with contains an installed running copy of Windows 10 onto a separate SSD. I placed this separate ssd into an USB 3 external enclosure and plugged it into my rMBP 14. By holding down option during the boot process, I can boot into Windows on the external drive. I installed bootcamp drivers and everything seems to run fine. Has anyone else tried using this process to get Windows onto their Mac? Any problems down the road?