What I do is connect an ethernet cable directly from my capture pc to CP5. And I use the Mach 2's internal cabling to connect USB and power to a Pegasus PPBA mounted on top of the scope for camera and devices.

 

And by the way, unless you are doing planetary imaging/video USB 3 is not really necessary. USB 2 is much more stable and reliable, being able to use longer cables. The speed difference in downloading images is barely noticeable.