Bootcamp with Additional Partition

I plan to use Bootcamp for a dual boot of OS X Mavericks and Windows 8.1 on my rMBP. I would also like to create an additional partition for my Documents/files. I understand that OS X doesn't like user files on a non-OS partition, but for Windows I like to keep my files/docs on a separate partition, to make backups easier and cleaner (backup OS Windows and docs/files separately).

I've read that adding an additional partition can cause problems with Bootcamp, and am seeking suggestions for a stable way to do this, either during or after the Bootcamp setup.

Any suggestions/help/advice will be appreciated!