Combine first 4 ingredients in a large bowl, stirring until salt and sugar dissolve. Stir in 2 tablespoons five-spice powder. Pour salt mixture into a large zip-top plastic bag. Rinse chicken with cold water. Add chicken and ice to bag; seal. Refrigerate 2 hours, turning bag occasionally. Remove chicken from bag; discard brine. Pat chicken dry with paper towels.
Combine hoisin sauce and next 5 ingredients (hoisin sauce through 1/4 teaspoon five-spice powder).
Prepare the grill for indirect grilling, heating one side to medium and leaving one side with no heat.
Place chicken, skin side down, on grill rack coated with cooking spray over medium heat side. Close lid; grill chicken 8 minutes on each side, brushing occasionally with hoisin sauce mixture. Place chicken, skin side up, on unheated side; brush with hoisin sauce mixture. Grill an additional 5 minutes or until done. Discard skin; serve immediately.