Is there a way to customize more than 9 range values in the heat maps?

This may not work unless you have a way to translate their regions into latitute/longitude, but those maps have more than 18 colors. Here's a quick example image I made using latitute and longitude.

No problem! How are the territories set up? By state?

So I do have a county + zip code + lat/lon spreadsheet (attached). You should be able to do a join on county names. Unfortunately it will only a show one point per row instead of filling the whole county with a color though. Since the midwest has way fewer counties/cities, it's much more sparse than the coasts. Here's an example of a map with 20 colors.