the short tail moment, associated with the drag of the two wings, slower airspeed and a Cg optimised for aerobatics, here is your problem,,,you need more deflection of the control surfaces, and it is therefore way too easy to over control it. Those Pitts and Christen eagle are known to be dogs to land..I would suggest some expo also, to tame the overcontrol trend, bring low, a little hot and chop the power when in ground effect...This means a long approach maybe.
My old Byron Pitts was such a bear, back in 1978
Good flying
Al