I’d have a different sense of elegance here, but - regardless - there are also other options:
Admittedly, some concentration is necessary to wrap your head around how the --pref-dir option works (see this topic), so that might disqualify it for the elegance competition.
So what I’d do (and in fact do) is to create a single repository for /share and exclude/include the folders you (don’t) want using the filters file.