I've configured various iterations of docking ports connected to robotic pieces, such as pistons, hinges, and servos.
There is a clear limitation to using docking ports on the robotic pieces, as testing on Kerbin constantly results in docked vehicles continuously jostling, shifting, and moving. This occurs regardless of whether robotic parts are locked, toggled on, or wheels of vechicles are powered, or brakes applied.
Before I spent any time exploring the Breaking Ground expansion capabilities on other Kealestial bodies, I did what any engineer would do: test first. As this feature has been broken since the expansion, I have not played KSP and have been waiting for this critical defect to be resolved.
After checking today, it appears that this behavior is yet to be resolved in game. In addtition, the Bugtracker actually marked it as a new low-priority defect, and burried it in the backlog. As these Breaking Ground robotic configurations are one of the major highlights of this expansion, marking a game-breaking defect as low-priority is a bit dumbfounding. I apologize for not including pictures, but anyone who configures two vehicles to dock on Kerbin with ports attached to robotic parts should be able to replicate, as seen in other posts above.
I've had much love of this project over the course of its development and maturation process. I hope that this latest expansion is not indicative of production quality going forward.