If Canon, Nikon and Phase aren't working on a electronic viewfinder system, then to paraphrase Ross Perot, that great sucking noise you hear is people moving to another platform. (well he didn't exactly say that).
Chris I understand why you went with the R version because most of what you shoot in stills isn't moving, but I do wonder why they didn't add the same focus capabilties to the R that they did the A7.
Anyway, Ive looked and investigated tethering and Sony says they have a solution, but doesn't make mention of how it works, or where it is. http://blog.sony.com/2013/10/a7-faq/"Yes the α7 and α7R offers tethering capabilities for still and video both Mac and PC but does not include Live View transmission.
For that, you’ll want to use the PlayMemories Mobile and Smart Control . These are pre-installed on both cameras."
If you run Windows or have an Android tablet, this company makes a software for tethering.http://dslrsoftware.com/tethered_shoot_lr5_a7_windows.php
Then again I don't know anyone that runs windows or Android.