Starting with the brine, fill a tub with one gallon of water. Add 1 cup of coarse salt, and stir in until fully dissolved.
Place chicken thighs in water, ensuring that the meat is fully submerged. Place lid on tub.
Transfer to refrigerator and leave for one hour.
Remove thighs from brine and pat down with paper towels. Transfer to drying racks or to dry paper towel surface.
Start up smoker and aim for cooking temperature of 225°F (107°C).
While smoker heats up, make the rub by mixing all rub ingredients in a bowl. Combine thoroughly and then apply to thighs. Apply generously and aim to work into all areas of the chicken skin.
Transfer thighs to smoker and close door/lid. Cooks for 2 hours at 225°F, or until the thickest part of the thigh has reached an internal temperature of 165°F (74°C).
Remove thighs from smoker and place on cooking surface. Apply BBQ sauce to thighs by either dunking them, or using a bbq brush to apply it.
Put thighs back in smoker and cook for a further 10-15 minutes.
Remove thighs from smoker and allow to cool for 5-10 minutes.