Unless there is an overriding reason to have more access than the UI3 web interface provides, then I would just run 2 instances of BI (on separate hardware) and view each instance's UI3 stream on a separate monitor at full screen.
There are very few things that a user/viewer would need that can not be made available via UI3. And this way the BI servers could be located in a more secure location than under a receptionist's desk (don't laugh, I have seen it)