rotated text attached to (i.e., after) final BarLine

[Kieren MacMillan]

Hello all!

I would like to put a piece of vertically-rotated text (a date/location stamp) 
after the last measure of my piece. (This is a common element of many scores, 
although I can't seem to find an example online at the moment, and I don't have 
a scanner.)

I have no problem building and rotating the markup, but I can't figure out how 
to attach it to the final BarLine and give it the correct 
spacing/padding/whiteout. I've tried adjusting BarLine #'space-alist, but 
without content "after the final bar", that doesn't work -- and I don't want a 
solution as hacky as adding an extra blank measure. I've also tried to override 
the BarLine #'stencil, to no avail.

Essentially, I would like my final BarLine grob to consist of the regular glyph 
(usually "|.") and the piece of text to the right of it, with the "bottom" 
(right-hand side when rotated) of the text block being up against the 
right-hand margin.

Has anyone else solved this already?
If not, any suggestions or thought-experiments would be appreciated.

Thanks,
Kieren.