Trying to investigate the influence of stabiliser vs. elevators thickness on altitude holding ability in level and inverted flight, turbulator strips of different thickness have been installed at the hingeline of the stabiliser. Repeated test flights have been conducted at governed constant RPM in calm conditions.
Peter, have you tried the conventional hinge line setup with the corners knocked off? Anything I did along the lines of what you are doing made it worse rather than better. Also, what tail incidence are you using?