I'm a competitive amateur in the south, and while you're right about wishing it were "more active" down here, it
is getting better. Birmingham, AL is a new NQE in February, there's an Atlanta comp in May run by the USA Dance chapter there; they'd like to become an NQE at some point. There are a couple of one-day, all-am events in Florida that are incredibly well-attended and growing every year. The Gumbo chapter in LA hosts a HUGE NQE in June that's widely regarded as the most fun of all the NQEs!
There are three comps in North Carolina that I'm aware of - the Carolina Fall Classic, which is held in early October, and then the Triangle Open, hosted by NC State, in November. There's also the Charlotte Dancesport Challenge, in April. Since the CFC is the NQE, it's the one that's most well-attended by all age divisions. I can't speak to the other two.
Now, your question about how well attended comps are for "non student amateurs": I'd go to the
O2CM results list, look up some of these comps, or others you have an interest in, and see who else danced in your events in your age category. Then you'd have a better idea of how many "(traditional) non students" (read: S1, S2, S3, etc) attend.