As most of Whitby owners already realize Whitby 42's are under-endowed in the rudder department.
The rudder indicator on the autopilot can be very handy to compensate for the problem of the mizzen or main overpowering the rudder.
Start by easing the mizzen, then dropping it, then easing the main until the indicator is as close to center as possible.
The Whitby will essentially sail itself like this especially on its favorite point of sail the "broad reach freight train", as we call it.
Running downwind with the autopilot is a different story as it needs careful attention.