Just got my home switches working.
I don't think it's safe to use the Safe Z setting, as there's no way to know if SafeZ is in work coordinates or machine coordinates.
Big Tex returns to just below the home switch, but if the user has a home switch offset, then that won't work either.
So I think the safest way is for the user to define the retract height above the fixed plate.
So you won't need the Z home switch. But you will need X and Y home switches, in order to know where the plate is.
Yes, there's a DRO for the plate thickness. In the Blue screen it's to the right and up a little from the other buttons.