RPU as Primary, console as Tracking Backup

I'm looking for info on what is normal practice when adding a Tracking Backup to a system, specifically where the additional components need to be to be usable mid-show if either the Primary or Backup go down.
We're looking at setting up a Tracking Backup by purchasing an Ion Xe RPU and running the RPU as Primary Master, and our Eos Ion Xe Console as a Tracking Backup.  The console will stay in the Tech Booth for shows and we will run the show from the console under normal circumstances.
This is the part I'm not clear on.  If the Console (Tracking Backup) goes down, the RPU (Primary) will have to be in the booth to be accessed? ...and will have to have at minimum a keyboard (for the spacebar for "GO" commands, etc.), a screen to see what is happening, preferably a touch screen, and perhaps a mouse, so the show can be run from the RPU if the console goes down (unlikely, if the console is the Tracking Backup, but still possible).
If the RPU Primary goes down then the console takes over (once we acknowledge the change by pushing the button that appears on the Backup's screen).
Also, when it comes down to it, is there much price difference between an Ion Xe Console, and an Ion Xe RPU?  Perhaps we should just purchase a second console?
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