I stopped in at Home Depot today to just check to see if they had any BBQ stuff out yet. It was fully stocked! One thing that caught my eye was a Weber Rib Rack. It says it fits the 18.5 and it certainly does, I tried it on a SJS that they had on display and it fit like a glove! It has 5 slots so with two of them on the 14.5 or a mini you could do 5 racks of ribs. It does fit on the bottom grate of the 14.5 and my mini.
CONS: The only thing I can see is that because the fit is tight, the half racks on the two ends might get their ends or even the entire half overcooked. Now I wish that instead of doing country ribs today I was doing a rack.