Glenn,
You might as well resign yourself to the idea of a gate. I am in a similar situation: my driveway is a bit over 1900 feet long. Even though there are only two more driveways before the access road dead ends, meaning not much traffic, people would drive on in, sometimes coming right up to turnaround in front of my house. When I asked them what the %@$* they thought they were doing, the most common answer was "I didn't see the signs" followed by "We were just looking around." I would give them the "There's always at least one person on the property, armed, so it would be a very bad idea to come back after dark" speech but it didn't seem to register on most of them. Soo.. I have to put up with the inconvenience of a gate because The Other Guy is an inconsiderate moron.
We have to accept the fact that people just don't read signs and most think that rules don't apply to them anyway. I don't think that most people are deliberately inconsiderate, they are simply unaware that there are other people in the world. It's a sad sign of the times.
rs,
Tack