Consider a staged approach:
One rule would find all counties with dealers and insert a (temporary) fact
for each, let's call them GoodCounty( County c ).
Another rule would match any GoodCounty and its wealthy Zips, obtained with
a from $goodCounty.getCounty().zips.
A third low salience rule would
There are certain domains where a collection of objects is itself a member of a
different collection of objects (e.g. zips in counties in states, persons in
cars at intersections). In these domains, it would be helpful to create LHS
conditions on the individual members of the "subcollection".
