end of a TextSpanner

[Stefan Thomas]

Dear lilypondusers,
how can I achieve the end of the TextSpanner together with the last shorter-rest in the below quoted example:
%%%%%% begin %%%%%%%
\version "2.11.49"
pedal = { \once \override TextSpanner #'outside-staff-priority = #500 
   \textSpannerDown
    \once \override TextSpanner #'bound-details #'left #'text = \markup { \musicglyph #"pedal.Ped" }
   \once \override TextSpanner #'bound-details #'left-broken #'text = ##f 
 \once  \override TextSpanner #'style = #'dashed-line
 \once  \override TextSpanner #'dash-period = #0.01
   \once \override TextSpanner #'bound-details #'right #'attach-dir = #1
     \once \override TextSpanner #'bound-details #'right #'attach-dir = #1 
   \once \override TextSpanner #'bound-details #'right #'text =\markup { \draw-line #'(0 . 1) }
   \once\override TextSpanner #'bound-details #'right-broken #'text = ##f 
      \once \override TextSpanner #'bound-details #'right #'padding = #-0.5 
   }
pedalisierung  = { \pedal s2\mf\> \startTextSpan s2\p s4..  s16 \stopTextSpan }

\relative { \context Voice << { c8 d e f g2 R1 } { \pedalisierung } >>  }
 %%%%%% END %%%%%%%%