Just me, I don't like mixing meats , where one meat will drip on a different meat. I guess having pork dripping on chicken would be no diff than wrapping chicken pieces in bacon. But I just don't like the idea.
But as to your question .................. five racks of ribs on a 22 WSM ? You'd have to use rib racks and get all five on the top grate, cuz two or three spatchcocked yardbird is gonna take up the bottom grate.
Here's two yardbird on the 22 WSM, making room for a rack or two of ribs on that , would be tough. And with three birds, no way.
And also, another thought, if you made room on the bottom grill for a rack of ribs, some of the meat is gonna get pushed to the outside edge and exposed to higher direct heat. In reality, that outside edge of the bottom grate is not really good for a long cook.