Hi Brent,
You can put the paper bloc in a bookpart, e.g.:
\version "2.20.0"
music = { \repeat unfold 100 s1 }
\book {
\bookpart {
\score { \music }
\header { piece = \markup\bold\fontsize #5 \fill-line { "15" } }
\paper { system-system-spacing.basic-distance = 15 }
}
\bookpart {
\score { \music }
\header { piece = \markup\bold\fontsize #5 \fill-line { "20" } }
\paper { system-system-spacing.basic-distance = 20 }
}
\bookpart {
\score { \music }
\header { piece = \markup\bold\fontsize #5 \fill-line { "30" } }
\paper { system-system-spacing.basic-distance = 30 }
}
}
HTH,
Cheers,
Pierre