tempomark at a multimeasure beginning

[coro]

I would like to have a tempo mark at the beginning of a violin part (from
a chamber work) that starts with multimeasure rests, but text width makes
the measure width bigger. Would it be a bug?

None of next options works with "R"



\version "2.10.20"

tempoMark = #(define-music-function (parser location markp) (string?)
  #{
    \once \override Score . RehearsalMark #'self-alignment-X = #left
    \once \override Score . RehearsalMark #'no-spacing-rods = ##t
    \mark \markup { \bold $markp }
  #})

\relative c' {
  s1*0^"Poco piu mosso"
  r1
  d e f
  s1*0^"Poco piu mosso"
  R1
  g a b
  \tempoMark "Poco piu mosso"
  r
  c d e
  \tempoMark "Poco piu mosso"
  R
  f g f
}