Mailing ahead was never a problem. We knew within a 2 week window when we would reach a town. It was fun talking to the post office folks in those small communities. Between them and UPS drivers you can find out where anything is located.
We were such a novelty in one small community that the postal person called the local newspaper. The paper sent out a person to take pictures, and interview us. I'm not sure if it was because we plan our own routes and stay away from ACA or other popular routes; or the fact that such an old guy could even get astride and pedal a loaded bike, much less be accompanied by such a good looking woman.