\break in arbitrary measures

Hi!

I wonder if this is possible. I have to extract PNG fragments from a bunch
of scores. I found the clip-regions variable in the \layout block and the
-dclip-systems command line option and they are exactly what I was looking
for BUT I need that each fragment begins a new system (in order to have
clefs, key signatures, etc.). Is there a way to «insert» \break-s using
some kind of function such as, for example, \predefinedBreaks = #(13 18 25
37) so that a \break appears at the end of measures 12, 17, 24 and 36? I've
asked IA models to no avail.

Thank you in advance!

F.