Dry rub: Mix together the dry rub ingredients and set aside. If using, reserve 1 tablespoon for the mop.
Trim off any access skin and fat from the chicken thighs: Keep the layer of skin that covers the top of the chicken thigh to lock in the juices, but trim off and discard any skin or fat that wraps around the underside of the chicken thigh.
Cover chicken with dry rub: Generously rub all sides of the chicken thighs with dry rub, including on top of the skin, under the skin, and on the underside of the chicken.
Preheat the smoker: Let the chicken rest while you preheat the smoker to 225-250 degrees F.
Smoke the chicken: Place the chicken on the smoker with the skin side up. Smoke the chicken for about 1 ½ - 2 hours, brushing the chicken with the mop after 45 minutes. Continue to mop the chicken every 30 minutes until the internal temperature reaches about 165 degrees.
Reverse sear: If desired, turn the smoker up to medium-high heat, about 450 degrees, and cook the chicken thighs skin side down over direct heat until nicely charred. Don't cook the chicken past an internal temperature of 170-175 degrees.
Rest: Remove the chicken from the grill and let rest for 10 minutes before serving.