I was very specific with the 400 ft ceiling in saying FPV Vehicles , if you flying a pattern plane at 1000 ft great typically on an RC field and your not two miles away using an FPV added system , this is the root of the problem , RC plane pilots fly withen an area that they can see , many FPV Vehicles are way out of sight and aided and controlled by FPV systems making them very dangerous to air space
How do you propose to enforce a 400' limit on FPV? I also might add I don't think FPV should exceed LOS operations either.