I don't see how the telltales vs sail, effect things for the autopilot. As long as the wind vane (PIDInput) is a bit in front of the jib (and the rest of the boat), it should not be affected by the boat itself.
Look at this picture 
I know it's not a sail and I know the airfoil is at a high angle of attack but it shows very well how the air ahead of the airfoil is already disturbed by it. It is only when you reach the speed of sound that undisturbed air comes in contact with the airfoil.
To repeat myself, I am not saying don't try it. I am saying don't spend a whole lot of time on theoretical PID tuning when the real input that you have to deal with will have a huge amount of uncertainty in it. I am also saying that I believe it will be difficult to get steering performance that is anywhere near as good as you can do yourself.
...R