Peter, you mentioned before that your Plus 8 produces spray inside the car. I have a roadster and I have seen the same, maybe to a smaller extend. I my opinion this I not caused by the rear or the shape of the body but from the windshield itself. Normal windshields are installed in a rather flat angle these days to reduce the drag by allowing the air to flow along the surface. Whenever the airflow cant follow the surface, it leads to turbulence. Since our windshield is installed upright, no laminar airflow is possible. If you position such a plate I an airflow, it will result in massive turbulences behind it and you will even find areas with backflowing air. This backflow will guide dirt and spray to the back of the shield and on the dash. It's about the same effect that you have with modern cars, the rear end is always dirty because of the turbulences there. The only solution for a Morgan is to remove the screen or adjust the angle.
