I would definitely shy away from the kitchen aid stuffer attachment and go with a dedicated sausage press. It is very helpful to load all of your meat as you grind it into the hover, then crank with one hand and mediate your grasp on the casings to get your desired sausage fill.
With the kitchen aid (and it’s tray style hopper) you will find the need to grasp the casings with one hand, load the meat with the other and almost need a third hand to keep the meat feeding into the machine.
It’s tough to explain but the sausage press is much easier. For the cost of the kitchen aid attachments, just get a dedicated device.
As far as a grind, I’ve taken the easy way out and asked my butcher to grind a pork shoulder and some bacon for me to get to the magical 80/20 ratio