I was using an un-used parking lot at a now, gone Mall back in the mid 90's. There was one entrance into the place, a good size parking lot and no light poles. So I parked across the entrance, and commenced putting flights in. One time I was in the middle of inverted laps and there was a car driving right at my airplane, windshield height. Thank goodness I rememberded bottom as I missed the old ladys car. She drove the perimeter of the the parking lot, got back to where my car was and jumped the curb, grinding on her frame, and drove off.
Always best to have a spotter but though we have a fair bunch of people who fly in Kansas City, we're all spread out and all workign different shifts. Takes me an hour to get to Shawnee Mission or to Lake Jacomo. We had more people in Topeka in the 90's and they were spread all over too BUT that means it takes about 15 minutes to get to the field.f
Stay alert.