Remove giblets from the duck cavity. Pat the duck completely dry with paper towels inside and out.
Using a sharp fork or poultry needle, prick the skin every 1/2 inch across the breast, thighs, and legs. Angle the punctures to penetrate through the skin and fat layer only — not into the meat.
Mix the kosher salt, black pepper, garlic powder, onion powder, and smoked paprika. Rub the mixture evenly over the entire duck, including inside the cavity.
Place the duck on a wire rack set over a sheet pan. Refrigerate uncovered for 8-12 hours. This dry brines the meat and dries the skin for better smoke adhesion.
Preheat your smoker to 225°F using apple, cherry, or maple wood. Set up a water pan to help stabilize the temperature.
Place the duck breast-side up on the smoker grate. Position a drip pan directly beneath the duck to catch rendered fat.
Smoke the duck for 3-4 hours, maintaining 225°F. If using the optional glaze, whisk together the maple syrup, orange juice, and soy sauce. Brush it onto the duck every 20 minutes during the final hour.
Check the internal temperature by inserting an instant-read thermometer into the thickest part of the thigh without touching bone. The duck is done at 165°F.
For crispy skin, increase the smoker temperature to 350-400°F for the final 15-20 minutes. Alternatively, transfer the duck to a sheet pan and broil 6 inches from the element for 2-3 minutes.
Remove the duck from the smoker and rest on a cutting board for 15 minutes before carving. Save the rendered fat from the drip pan for cooking.