Hand not on the rudder control causes wandering and this is normal.
I am surprised deploying the skeg does not help tracking as that's why Hobie made the change.
My 2013 PA-14 does not have a skeg and I down rig fish 90% of the time. Until I installed the sailing rudder, I had trouble keeping on track.
You can also check the rudder centering by placing the hull on sawhorses. If the rudder handle is not quire right, uncover the rudder housing and adjust the spectra lines. Hobie has a detailed set of instructions to accomplish this starting on page 28 below.
https://media.hobie.com/digital_assets/ ... 140429.pdfAre you using the rudder BOA to take slop out of the rudder lines when the hull is cool and then loosing it when the hull warms up and expands?
Also, make sure the skeg is fully deployed while you are at it.