kwas68, I guess there will be three judges... Cook a couple racks, choose the best three ribs. Look for straightness of bone, meatiness, great glaze, etc. Then, being careful to make a straight, clean cut, slice through the rack as close as you can to the two ribs on either side of the perfect rib. This will give a nice chunk of meat on each side of the rib. You might consider a dense parsley bed and orient the rib from front to back. That way when the table captain (if there is one) tilts the box for the judges to see, the rib won't want to roll on its side.
I did notice that it says "at least one" it's not unheard of to put more meat in the box than required. That is, if you have enough gorgeous ribs to put two per box.