Using a sharp knife, "square off" the pork belly until you have a rectangular piece roughly 12 inches long and 6 to 7 inches wide. (You can cure and smoke the trimmings alongside the bacon or use them to flavor beans, soups, collard greens, etc.)
Lay the pork belly on a rimmed baking sheet lined with a sheet of parchment paper or waxed paper. Brush or spray on all sides with some of the bourbon, reserving the rest.
Make the dry brine: In a small bowl, thoroughly mix the kosher and pink curing salts. Stir in the brown sugar, black pepper, and garlic and onion powders. Sprinkle the dry brine on all sides of the pork belly and massage it into the meat.
Transfer the pork and any remaining brine to a large resealable plastic bag. Put the bag on the sheet pan (in case the bag leaks) and refrigerate for 7 days, flipping the bag each day to redistribute the brine and accumulated juices.
On Day 7, rinse the pork well under cold running water and pat dry with paper towels. Refrigerate until ready to smoke.
When ready to smoke, start the Traeger grill outfitted with a Traeger Cold Smoker on Smoke with the lid open until the fire is established (4 to 5 minutes). Close the lid and allow the unit to run for 10 to 15 minutes.
Spray or brush the pork belly with the reserved bourbon and put it on the Cold Smoker rack. Smoke for 3 to 4 hours, maintaining a temperature between 70 and 100. Periodically reapply the bourbon. Increase the temperature to 180 to 200 and continue to smoke the pork for 1-1/2 to 2 hours, or until the internal temperature of the pork when read on an instant-read meat thermometer is 150.
Transfer the bacon to a wire rack to cool completely, patting any beads of fat off it with paper towels. Enclose in a new resealable plastic bag. Chill overnight, then slice with a long sharp knife or a meat slicer.
Repackage the bacon, then refrigerate for up to 2 weeks or freeze for up to 3 months. Cook before eating.