Graphical rallentendo

[Jacques Menu]

Hello folks,

Is there a more natural way of obtaining this result than with a sequence of 
shorter and shorter skips?

Thanks for your help!

JM


%%%%%%

\version "2.23.5"

\relative c''' {
  \time 6/8

  <<
    {
      g8 ^\markup {\italic "rit." }  g4  g8
      g4  | % 16
      c8 [  bes8 (  g8 )
      e8 (  c8 )  bes8 _\laissezVibrer ]
    }
    {
      \once\override TextSpanner.style = #'trill % wave zigzag
      \once\override TextSpanner.minimum-length = #8
      \once\override TextSpanner.Y-offset = #-4
      \once\override TextSpanner.springs-and-rods = 
#ly:spanner::set-spacing-rods
      { s2. \startTextSpan s2 s8... s64 \stopTextSpan }
    }
  >>
}

%%%%%%