Best cable to carry 3 DP (differential pairs), power, ground and 4 signals
I can confirm that a miniDP cable is capable of what I intended to do.
The only thing is, power should not be carried by pin 20, since in most (if not every) commercially available cables, it's an unconnected pin.
So you have to choose another PIN to carry Power.
At the moment I am using pin 2 and 19 (for redundancy)
The setup works