layout questions

[David Bobroff]

I'm typesetting from an ugly hand-written part.  It's a trombone part to 
an orchestral piece and, therefor, consists largely of multi-measure 
rests.  I'm using the contruct:

\textLengthOn
s1*0^\markup{ whatever }
R1*X

...to stretch the multi-measure rests to fit the length of the markup.  
So far, so good.  In some cases, however, rehearsal marks are being 
"pushed" up out of the way of some of these markups.  I've tried 
sneaking the global font size down and increasing the number of 
systems.  This seems to have fixed some/much of the problem.  I would 
like a way to have them all at the default distance from the staff ( = 
one staff space?).  I'm not sure where to find my answer.  Should I be 
tweaking the length of individual multi-rests?  Should I be adding 
side-padding to the markups?  Is this a job for outside-staff-priority?

Thanks,

David