It is not just how the model looks. I believe the real F-16 has the center of mass behind the center of drag so it would tend to swap ends if not for the computer controls. The model would only need weight distribution to move the center of mass in front of the center of drag. The tail even increases the drag behind the center of mass if the model starts turning a bit sideways.
Depends on the configuration of the aircraft as well. Had an F-22 tell me once that the Raptor is stable in take off and landing configuration (gear and flaps down) but unstable in flight config.