O'Boy! Another 400' argument!! Been there, done that, and left that Club. We even had the local ATC controlled airports permission, but the management dictated the 400' That is because no one can accurately measure 400' by sight. Look at your runway and measure it, stand it on end to give you an idea. But, in truth, only way is telemetry. I'm not sure how accurate that is either, due to pressure altitude and density altitude, if the telemetry is read off of a pressure switch.
Best thing to do it is to "notify the local airport management, or ATC" as per AMA recommendations to fly above the 400'. Otherwise, this argument will do nothing but to destroy the friendly feeling at the Club, and create distention amongst the members.