I have always found it a bit unwieldy when shooting in a vertical/portrait orientation with a tethering cable attached. Recently, Really Right Stuff (RRS) made the perfect solution and I was fortunate to shoot with the Cable Release Spacer (CRS) today.
The CRS attaches to a standard L-bracket and adds about 1.25" for your tethering cable. It also has a small locking bar to "lock" your cable to the spacer. This is great since any tugging on the cable can easily damage your camera's ports, a very expensive fix by the way.
Vertical orientation. The CRS firmly attaches to your L-bracket for stability.
Horizontal orientation, not much change but cable is firmly attached.
If you are a tethered shooter and are tired of dealing with work arounds for your cable when shooting vertically, pick up a RRS Cable Relief Spacer and all is good.
Click here to visit the RRS site.