Hyphens before and after finger numbers

[David Raleigh Arnold]

Please, how can I get the same numbers with the hyphens as without?  I've only 
been trying to do it for four years or so.  I'm not the only one.  The 
hyphens are much nicer than dotted ties or those horrible straight ruled 
lines between numbers.

\version "2.2.6"
\include "english.ly"
\paper { papersize = "letter" }
#(set-global-staff-size 20)
sig = \override Staff.TimeSignature   #'style = #'()
mrgd = \override Staff.NoteCollision   #'merge-differently-dotted = ##t
mrgdr = \revert Staff.NoteCollision #'merge-differently-dotted
mrgh = \override Staff.NoteCollision   #'merge-differently-headed = ##t
mrghr = \revert Staff.NoteCollision #'merge-differently-headed

%#(set-accidental-style 'voice)
% @s is force-hshift in sly, to revert: \\sr
%sr = \revert NoteColumn #'force-hshift % revert force right
ih = \override NoteHead   #'transparent = ##t % invisible head
vh = \revert NoteHead #'transparent  % visible head
ld = \stemDown
lu = \stemUp
ft = \markup{"t"}
fi = \markup{"i"}
fm = \markup{"m"}
fa = \markup{"a"}
aha = \markup{\bold "1-"}
ahb = \markup{\bold "-1"}
mlau = { \once \override DynamicText
         #'extra-offset = #'(-3.5 . 2.5) }
botpart = \notes { 
\stemDown \tieDown \slurDown \dotsDown \tupletDown
\clef "G_8"
\key c \major 
\sig 
\time 4/4
\mrgh
\override NoteColumn #'force-hshift = #-0.05
\mlau  c2_\f e2
a, c
}
toppart = \notes { \stemUp \tieUp \slurUp \tupletUp  
\ih c8_3^\ft \vh g^\fi c'_\aha^\fm e'^\fa \ih e8_2 \vh g c' e'
\ih a, \vh a_\markup { \finger "2-" } c' e' \ih c \vh a c'_\ahb e'
 \bar "|."
}
\score {
        <<
 \context Staff = guitar <<
  \set Staff.instrument = #"\\Large{1.}"
  \context Voice = bass \notes {   
   \botpart }   
  \context Voice = top  \notes {
   \toppart }
  >>
>>
 \paper {  linewidth = 7.25 \in
   indent = 0.25 \in
   interscoreline = -3
  }
 \midi  { \tempo 4=94 } % will be unison errors
}