My family calls this dish a "Heart Attack on a Plate" But they sure eat it up quick. This dish can be cooked in the oven in a roaster pan or in the Slow Cooker, either way you cook it..it is delicious.
In a large mixing bowl, add box stuffing, sage, pepper, paremsan cheese, and melted stick of butter. Mix well. Add some chicken broth (instead of water) to moisten stuffing enough to resemble stuffing you make to stuff a turkey with. Let set.
In a skillet cook sausage and onion together until done. Drain off fat and place in a food processor. (don't process yet) Fry 3-4 slices of bacon in same skillet until done. Put bacon in the processor and chop fine. Add to stuffing add cheddar cheese and mix well.
Put Pork loin on a work surface with a sharp knife cut the seam where pork loin comes together and lay open a rectangle slab of meat. Lay some wax paper down and with a rolling pin and some pressure thin meat out a little without breaking the flesh.
Shape a log shaped row of stuffing at one end of loin. Roll meat as you would a jellyroll. I tie both ends with cotton string. Lay bacon over loin in criss-cross lattice fashion to ensure bacon stays without using toothpicks (this technique works very well) it also ensures that the meat will stay moist due to the bacon drippings leaking into the meat.
Place in a roasting pan with a lid in a preheated 350^ oven and cook for 2 hours. Usually under the lid the bacon will crisp, if it doesn't take lid off 15 minutes prior to meat being done and let bacon crisp.
This dish can also be cooked in a slow cooker. Place in a slow cooker and cook on High 5-6 hours (bacon browns just as well in the slow cooker) or on Low 8-10 hours.