The early PAs had a smaller steering drum and the steering was a bit twitchy. Hobie made a running change to a larger drum and has also made this available to the early boats at no charge. See your dealer for details.
Winglets work better at higher speeds. On most kayaks it wouldn't be very effective at speeds lower than 5 MPH, but on the PA, the water passing over the rudder is slightly accelerated, so a wing might still have a noticeable effect at slower speeds. Someone would have to give it a try. I mentioned it since there isn't a larger rudder available, this is a way to effectively increase the area of the rudder a small amount while retaining the original set-up.
The PA has a lot of surface area above the waterline, so wind and swells are going to have a larger effect on course heading, especially at slow speeds where rudders always have less authority.
IMO, rudder placement rather than rudder size is a significant reason for poor tracking. Additionally, the hull has weak directional stability in order to achieve excellent turning. Considering the overall design, it would seem to be an inevitable characteristic of the boat.