I would go with the 12" mount on a Parker. This way you get the beam higher and above the heads of those in cockpit. With the lower roof line due to the step down into the wheel house it is probably best to elevate higher so the transmission beam isnt going into the heads of those in the cockpit. It is not good for you, especially your eyes. This is of course unless you are going with a solid state radar, which is said to be safer. Then I would still go taller unless you are trailering.