+1 for the Startech powered usb cable solution. I use 3 5 meter powered cables to go from my bicycle hydro/ wind trainer to my desktop computer to the cycle-ops software and it actually works.
I haven't tried the Startech and so I can't comment on them.
What I can say though is that every cable I had bought, being a 3m unpowered cable and a 5m powered cable all worked fine on file transfers to a self powered USB drive attached at the end and none worked with the camera. There are multiple things affecting connection such as power consistency, latency etc.
So because cables work with some things does not mean they work tethered to cameras.
The TetherPro cable is 4.6 metres unpowered and works.
So whatever solution you want to use you need to physically test it before buying.
The other thing to consider is that if the cable is powered by the computer then it will drain the laptop battery faster.
You also need to check that the computer is not actually powering the camera. On the X1D there is a setting for Powered by USB.