I want to put in a plug for the Moped Riders Directory if you haven't already checked it out. You can search for people with Moped Army profiles by state, city, and brand of moped. Results are sorted by the last time they logged into the website, which at least gives you some sense of whether they are still active or not.
I know it's not perfect. What would make it more useful to find moped riders near you? What if you could indicate on your profile that you're open to being contacted by moped riders in your area? Would that help to connect people or make it more comfortable to PM a stranger?