The only clearance you can change is between the last fixed wheel, and the wheel attached to the adjustable section of the carrier. With a 1600 series machine the long end of the carrier should be toward the front of the machine with the front carriers, and toward the rear end of the machine with the rear carriers. So the adjustable section should be the furthest forward wheel in front, and furthest aft wheel in rear.
P.S. Nice looking machine!