For the cut you are talkig about with using every other bone you will need at least 2 racks for your box if you want all the bones straight. On the St. Louis cut ribs they use the spare ribs with the cartilage end cut off along the bone. If you look at the bones before you cook them you will see one end will have 6-7 bones straight, then as you keep going the bones will start to curve. So if you are doing the double cut and want them straight you will lose about 1/3 - 1/2 of the rack to present. You then end up with 3-4 presentation pieces per rack.
Not sure what circuit you are competing in, but the FBA circuit does not use the green stuff in their boxes. I have judged a few in that circuit and have not heard any knock for the sigle cut or curved bones. I have seen plenty get knocked for sloppy boxes with horrible knife work, swimming in sauce, sauce all over the inside of the lid of the box and even black ribs.
For me in anything I do in any of my kitchens or have my Team prepare that requires knife work. A sharp appropriate knife is a must. A sharp knife will allow you to cut without much pressure. The appropriate knife will get you a cleaner looking cut.
When you are slicing a large cut of meat or anything really, each time you change direction you will leave a slight line on the product. A sharp appropriately sized knife will allow you to change directions less. If you look at a brisked when It is cut with a sharp appropriately sized knife properly you will only see a couple of these direction changes at most, best is only one. Then if you look at one with a wrong sized or dull knife it will look like it was cut with a chainsaw.
What is funny is listening to judges make comments on the knife work and they themselves do not know what was wrong, just that it looks ugly.
Hope this helps a bit......
Jeramy