Can you install Windows 7 64 on an iMac 5K with a 3TB fusion drive running Yosemite?

I've been trying for the better part of a week to install a Windows 7 X64 BootCamp to a refurbished iMac 5K with a 3TB fusion drive.

I was finally able to get a bootable Windows 7 partition, but attempting to migrate a 2TB mac clone back to the Mac logical volume hung. I erased the Mac logical volume and tried again, but it hung again.

The spinning drive looked like

EFI

Main 2 TB

Recovery 650 GB

Bootcamp 200 GB

Main 811 GB

and the Main Mac partition was apparently glued together by Core Storage from the SSD and both segments of Main on the spinning hard disk.

Is Core Storage a well enough baked LVM to handle this?

My iMac is back at the shop, but when I get it back is it worthwhile trying this again? Has anyone successfully done this in Yosemite with a similar configuration?

I could survive with a WIn7 64 virtual machine, but I'd really like to use boot camp so I could do some Windows 1440p gaming.

-- Thanks, Verne