This is the post wlfpkrcn is referring to:
"The stacking system works very well (nnn ribs), I’ve used it many times and it produced moist and tender ribs. But I have a better way of doing a lot of ribs at the same time without having to rotate them. This way does not require longer cooking time either.The best way I can describe it to you by using this picture:
Forgive me for using wood rods to illustrate this method, but I don’t have any ribs on hand. You’ll have to imagine that each rod is a rib rack. You can stack them as high as your smoker can handle (in the same order). You can also have two stacks next to each other’s. The gape in the center serves 2 purposes. One it allows the smoke to mingle among all the racks, and two it gives you room to spray the entire stack of ribs during smoking without moving any of them. If you’d like to try this, let me know if you have any questions about it. I don’t know how big your smoker is, but I would stack them up in the square fashion for a try out first. If they fit, then use it. I promise you the results will be excellent.