Welcome to the club of Amerique owners! With your plan, you will be safe, but here's the problem. The AQ is so well insulated and so well sealed that when the cooker goes to 140F for "holding," the temp falls VERY slowly, so overcooking is a problem. I discovered this on one of my first rib cooks. I think CS oversells this feature, and I never use it anymore. Now, when the ribs pass the toothpick test, I pull them, wrap them in double foil, and put them in a 200F oven until serving time, up to one or two hours only, then they start to dry out as more fat renders even at 200F. You could also try FTCing them if you need them to hold longer, but might have to reheat to serve.
I'd recommend trying some ribs for cooking time and cutting it a bit closer to serving.
PS: My baby backs (mostly from Sam's Club) usually take about 5 1/2 hours or longer at 225F. Just a heads up.