Changing vertical extent on-the-fly?

[Michael Käppler]

Hi all,
I recently asked a similar question on the list, now noticing again that 
I'd like to have this feature.
A minimal example:

\version "2.11.37"

\score {
\relative c' { <<
 \new Staff { c4 d e f | f e d c \break |
 \override Staff.VerticalAxisGroup #'minimum-Y-extent = #'(-8 . 4) % 
does not work
 c d e f | f e d c | }
 \new Staff { f4 e d c | c d e f | f e d c | c d e f | }
>> }
}

Is it possible to change minimum-Y-extent for a Staff on-the-fly like in 
the example?
Maybe something with NonMusicalPaperColumn could do the job the same 
way, but I don't really know how to figure this out at this time.

Thanks for all advice,
Michael