Dick H. should be able to answer your question with his experience level in the big machines.

With the big machine there is a lot of spiral airflow from the propeller. There will be an asymmetric flow on the vertical-rudder combination. If you have trimmed it level in normal flight be sure the ailerons and rudder arn't working against each other. Such that removing the right rudder allows the left aileron become effective. Check that the wings are not warped, vertical and horizontal tails are straight and not warped. Be sure all controls move the same amount and are set absolutely at neutral.

I do know that a lot of full scale machines have a slightly offset vertical fin to get a balanced level flight, and some use trim tabs on the ailerons.

With a Citabria you might look at what the real one requires and or flys like. There might be a site somewhere that describes it. Meanwhile you need a guy that has trimmed out a big model.