Preheat your smoker to 275°F to 300°F using your chosen wood chunks or pellets.
Unroll the boneless thighs and trim away any large, loose pockets of hard fat. In a small bowl, mix together all the rub ingredients. Season the thighs generously on all sides.
While the smoker finishes heating, combine the bourbon, maple syrup, Dijon mustard, apple cider vinegar, and Worcestershire sauce in a small saucepan over medium heat. Bring to a gentle simmer for 5 to 7 minutes to burn off the sharp alcohol edge and let it reduce slightly. Whisk in the butter until melted and glossy, then remove the pan from the heat.
Place the seasoned thighs flat on the smoker grates. Close the lid and smoke for 30 to 35 minutes, or until the internal temperature in the thickest part of the meat reaches 155°F to 160°F.
Generously brush the warm maple-bourbon glaze over all sides of the chicken. Close the lid and let them smoke for another 5 to 10 minutes.
Remove the chicken from the smoker the moment the internal temperature hits 170°F to 175°F. Let them rest for 5 minutes and drizzle with any extra glaze left in the pan.