metronome mark question

[James Bailey]

So, I've been thinking about this, would the easiest way to create a  
metronome mark that's barline aligned that plays back in midi be to:
• left-align the rehearsal mark with  \override Score.RehearsalMark  
#'self-alignment-X = #-1
• create a manual metronome mark using the \mark \markup {}
• hide the MetronomeMark with \set Score.tempoHideNote = ##t
• create a tempo indication using \tempo

Using this idea, I've come up with the following. Am I going about  
the wrong way, or is there an easier way?
\version "2.12.3"

test = {
   \override Score.RehearsalMark #'self-alignment-X = #-1
   \mark \markup {\concat { \smaller { \general-align #Y #DOWN \note  
#"4" #1 }  = 80 }}
   \set Score.tempoHideNote = ##t
   \tempo 4=80
   h4 a g f
   \mark \markup {\concat { \smaller { \general-align #Y #DOWN \note  
#"4" #1 }  = 60 }}
   \tempo 4=60
   h4 a g f
   \mark \markup {\concat { \smaller { \general-align #Y #DOWN \note  
#"4" #1 }  = 100 }}
   \tempo 4=100
   h4 a g f
}

\score {\test \midi {} \layout {} }