How to bring two staves close enough together to allow for overprint?

[Trevor Bača]

Hi,

In the following snippet I want the two staves to be exactly 5 staff
spaces apart even though this will cause the g'4 in the bass to
overprint the c'4 in the treble. But it doesn't work.


%%% BEGIN %%%

\version "2.11.20"

\new GrandStaff <<
  \new Staff \with {
     \override VerticalAxisGroup #'Y-extent = ##f
  } { c'4 }
  \new Staff \with {
     \override VerticalAxisGroup #'Y-extent = ##f
  } {
     \clef bass
     \overrideProperty "Score.NonMusicalPaperColumn"
     #'line-break-system-details #'((alignment-offsets . (0 . 5)))
     g'4
  }
> >

%%% END %%%


What are the correct settings to *absolutely guarantee* that the two
staves are 5 staff spaces apart (regardless of the musical content of
the staves ... thereby allowing for overprint)?


--
Trevor Bača
address@hidden