If you contact the ISUAA, they will have an estimate of how many people are in the area, and how many people that are subscribed to their emails. I started a gamewatch group here in the Raleigh-Durham, NC area a few years ago. They were pretty helpful in getting us established as an "official gamewatch location". We've been pretty active, and now we're a ISUAA club. There are 800+ alumni in the area, 300 of which subscribe to the ISUAA email announcements for gamewatches and other events. We range in football gamewatches between 15 and 35 people, depending on the match-up.
Contacting the ISUAA is the easy part. The hard part is establishing an "official" gamewatch location. Around here almost all of the good sports bars already had alumni groups and couldn't take on any more. When you look for one, make sure they can
guarantee your group a TV and tables for every game. If you tell the sports bar the stats for Nashville from the ISUAA, it might be a good selling point as essentially free advertising for their group.
Edit:
Here's your contact for the ISUAA.
http://www.isualum.org/en/about_us/isuaa_staff/tillie_good/