Like GLH says,but keep in mind that there is no "rule" that ribs have to have X amount of space between slabs,or can't ever touch.
They are going to be in the cooker for several hours,and as long as the air flow isn't completely blocked,heat and smoke will get to everywhere.
They may have to be shifted more often,and the door opening means you add some time at each shifting,but just plan for it.
You can buy disposable grill racks and put small blocks between them,like the jerky guys do.
Just a couple of thoughts.