add cobblestone underfill to entire town.
add code to truncate town-area if a long-strip (greater than 2:1 ratio)
area is detected.
...
add 'empty plot chance' setting for interior plot generation.
integer-percentage of a plot completely skipping generation; for housing
and cosmetic passes only.  Does not close the plot, merely skips (so the
same plot might skip housing, but not skip cosmetic).  
Will likely require fairly high values to see a noticeable decrease in
generation.  Might not work entirely as intended, as I might need to
track for a plot whether it was 'skipped' or not to skip further passes
for that plot, while still leaving 'open' for expansion from nearby
plots.
clean up town plot skip setting, add a skipped field to town-plot
objects, reference this field to decide whehter to skip on subsequent
passes over that plot (housing->cosmetic passes)