Tempo marking pushes rehearsal mark far above the staff

[James Harkins]

Sorry if it's a basic question -- my eyes are starting to glaze over
from looking at the manual.

In this minimal example, there's a collision between the rehearsal and
tempo marks. LP resolves the collision by pushing the rehearsal mark
rather far above the staff. This is a legibility issue when there is
more than one system, because the rehearsal mark is closer
(underneath) the preceding system than it is to the system that it
actually belongs to.

\relative c'' {
  \set Score.markFormatter = #format-mark-box-alphabet
  c4 c c c
  \mark \default
  % Note, I'm putting the tempo change here instead of bar 1
  % b/c my piece changes tempo in the middle,
  % often at rehearsal marks
  \tempo "Andante" 4 = 72
  \repeat unfold 3 { c4 c c c }
}

If I comment out the markFormatter line, then the rehearsal mark
appears just to the left of the tempo mark (with vertical centering),
but there is not enough horizontal distance between them. It almost
looks like "AAndante" (except that the first "A" is slightly larger
and its baseline is a little bit lower). For this case (no box), I
also tried these two (separately):

  % Pushed the rehearsal mark higher, possibly usable but not ideal
  % This had no effect on a rehearsal mark with box
  \override Score.RehearsalMark #'padding = #'4

  % No discernible effect, even with much larger numbers
  \override Score.RehearsalMark #'extra-spacing-width = #'(+inf.0 . -5.0)

I like the appearance with the box better. What I'd really like is for
LP to resolve the conflict by pushing the tempo mark to the right just
enough to avoid the rehearsal mark's horizontal padding.

TIA,
hjh