I have mine mounted at the back side of the captain's seat, it's far enough ahead to fight fish up the side of the boat, and the lines have never been close to getting into the prop. I would say they are approximately 6' ahead of the transom. When I used tube style holders they were mounted further back and in the way of landing fish. If your holders are further back you are forced to land fish back by the motors giving you a better chance of getting in the props.
Good luck
Keith