Are you using a 10 hole adjuster? What hole are you in? How much tiller tug (apparent weather helm) do you have?
I have a 10 holer and sometimes add a shackle to the end of it. I do not have any shackles on my bridles, however.
I like about 12-16 inches between the clew and the rear beam, depending on wind and instinct, which is hard to define.
My helm is close to neutral, just slightly weather.
