How did you manage to cut the backbone out? A bone saw? I've been thinking about smoking a turkey in my rig, but I'm not sure if the thing would fit, unless I get the rotisserie attachment and remove the grids completely.
I used a good heavy set of Poultry Scissors. A good sturdy steak knife would work, but I suggest folks use the poultry scissors, as they are safer. In the vid you can see the ones I used.