If you want to test the bombsights, bomb from at least 4000-5000 meters of altitude. The problem was that the bombsight was missing the high altitude adjustment for bomb trajectories, so if you bomb from low altitudes you are not really testing much
I did a very quick and dirty run: start the FMB, place two waypoints, Ju88 airstart with a full bomb load.
I am pleased to say that even though i was being very very sloppy (i was in a hurry), i still managed to get half my bombs within the perimeter of Manston.
I will do more testing tomorrow. I think that in a normal situation (well trimmed aircraft, time for the autopilot to settle, etc, instead of airstart and rushing to set engines, bombsight and bomb release settings in half a minute like i did in my test) it will be possible to accurately bomb from 5000 meters or more. Especially if you have wingmen with you to saturate the target.