We've got two different situations being described in this thread. And they're worlds apart.

When our models go into almost zero airspeed flight almost all aerodynamic rules are turned off. The airplane is being dragged around by the prop and any movements come from prop blast on the large surfaces and their large deflection. And ideas like roll couple really don't apply like they do when the airplane if flying. So basically all the things LDuck said about things like roll couple are true in flight. And relative location of surfaces do matter in flight as stated.

Flight is a different world than 3D. And aerodynamic things are well known for flight.

And we need to be clear in these discussions if we're talking flight or 3D.