Double check with local code office and double check what code you are under. I thought most of Mizzouri was under ICC (International Code) havn't been to many places where National code applies. But in KS and MO it has either been ICC or UPC (Uniform Plumbing Code)
ICC- Allows AAV
UPC- Does not allow AAV
Keep in mind that even if under any code that allows or prohibites AAV's the local authority can amend the code to reverse the code.
Just check with local authority
John Wayne once said "Life is tough and it is even tougher if you are stupid"