Creating a music function for staff to staff spacing

[Knute Snortum]

Hello everyone,

I need to control staff to staff spacing by system and I can do that (as
the documentation states) by separating the breaks into their own voice and
using the line-break-system-details of the NonMusicalPaperColumn. However,
this is a mouthful:

\once \override
    Score
    .NonMusicalPaperColumn
    .line-break-system-details
    = #'((Y-offset . 30)
         (alignment-distances . (15)))

So I am trying to create a music function where I only need to pass the
Y-offset and alignment-distances (I just need one), but the function isn't
working.  It doesn't throw an error, but it has no effect. I'm
hoping someone can correct my error.  Here is the code I'm using:

%%% Start
\version "2.24.4"

staffStaffSpacing =
#(define-music-function (off dist) (number? number?)
   #{
      \once \override
        Score
        .NonMusicalPaperColumn
        .line-break-system-details
        = #'((Y-offset . off)
             (alignment-distances . (dist)))
   #})

rightHand = \relative {
  \repeat unfold 16 { c'1 }
}

leftHand = \relative {
  \clef bass
  \repeat unfold 16 { c1 }
}

forceBreaks = {
  s1*8 \break
  \staffStaffSpacing #30 #15
  s1*8
}

\score {
  \new PianoStaff <<
    \new Staff \rightHand
    \new Staff \leftHand
    \new Devnull \forceBreaks
  >>
}
%%% End

--
Knute Snortum