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What you asked for is the Cam Ranger
While it has electronic camera control, T/S lenses are fully manual focus, tilt and shift.
However, Camranger gets the Live View off of the camera USB port, which has limited resolution. This has been covered in related threads.
As your TS lens movement use becomes more refined you may likely desire much higher resolution for low angle tilt adjustment than what the CamRanger can provide. High resolution Live View, comparable to the 5DIII Live View LCD, requires taking the signal off of the HDMI camera port and optimally scaling with software to maximize the inherent detail. Also Tilt adjustment requires two hands, one to loosen the lock knob and one to move the tilt knob. Don't try to force the tilt adjustment with a partially locked lock knob, this is courting an expensive repair as the mechanism has been known to freeze requiring a service visit. Adjustment of low angle tilt requires fine iterative adjustment of tilt and focus in conjunction with moving the magnification area about the frame to near field and infinity. I personally found that anything less than a full HD viewing screen (1280X800 and 1:1 scaling) to be inadequate. My approach with an HD capable external monitor is described in detail here, which covers the salient issues in greater detail:
I would get the lens and do lots of testing with Tilt and Shifting movements around home before worrying about an external display. It takes awhile to figure out what type of shots are facilitated with the lens movements what fov is attractive to you and what the demands on your equipment will be. I have found all viewfinders inadequate for critical tilt adjustment and use magnified Live View. As you get a lower and lower camera placement you will develop a feel of what type of Live View display will work for you.