You mentioned being armed-were you CCing or OCing? The latter tends to have better effects for your situation.
Also, someone else mentioned a border patrol patch, maybe some kind of law enforcement t-shirts(make sure you can legally wear them if you're not an agent or officer). I used to live in NoVA, and a relative wore a shirt like that into a 7 eleven. Before he goes in, the parking lot is full of day laborers, after he gets a drink and comes out, poof! parking lot is empty. All the NoVA people know what I'm talking about with 7 Elevens.
The Hispanic thing plays a role in NoVA because most can't speak any English.
You could also file with Fairfax PD, but if you don't already know they're becoming a sanctuary county. They don't want to deal with any illegal alien issues unless they absolutely have to.