This is really easy to do though, as long as you don’t need the number before the system and rehearsal letters in the same project. I’m actually working on a file where I use this right now. In Engraving Options / Rehearsal Letters:
Sequence Type: Numbers
Custom Suffix: .
Position of rehearsal mark at start of system: Left-aligned with systemic barline
Horizontal offset for ^^^: I use -3.5 spaces, but this will depend on your font
Minimum distance outside staff: I use -3, but again will depend on your font and the look you want.
After all that is set I get this with no manual editing at all:
(Currently revising my notation handout for student transcriptions before the semester starts.)