When using only betting exchange how do I see total vcash?

Unless you understand programming, there is nothing you can do as there are a lot of methods/functions that would need to be modified/re programmed in order to run the Betting Exchange feature of Sportsbook as a stand alone addon (which is what you are wanting to do). The Betting Exchange is feature of Sportsbook, not a stand alone completely separate addon. You can run Sportsbook alone without the Betting Exchange, but not vice versa (as the betting exchange is PART of Sportsbook and depends on internal framework functions like the built in cash system for instance). With that said, there have been some enhancements made in the next 2nd point release that give the appearance of separation and should be able to handle what you are wanting to do.

What you CAN DO (for now) is HIDE the navigation tab for Sportsbook (via CSS) (there are a ton of threads on how to hide navigation tabs at xf.com) OR you can disable the navigation tabs listener for Sportsbook (advanced task, but probably better result).