I didn't think about this until now, but the HTC Vive has an extra USB 3.0 port in the HMD, right next to where the cables connect. I didn't have a clue why, until I saw the Leap Motion Dev Kit.
Attachment 3011
For only 10USD more than the controller, you get a HMD mount that works on Vive and Rift. Instead of having another 15 foot cord, take a 9 inch one and use that port! HTC was actually thinking on this one!