About 8 years ago, when injecting meats became popular, I made my turkey this way for Thanksgiving. I have never roasted a turkey since. It turns out so juicy, tender and delicious. The slight smoke flavor compared to a fully smoked turkey is just right in my opinion. Fully smoked turkeys can be a little overbearing when served with the usual Thanksgiving fare. By BBQing it you have room in the oven for the side dishes. I usually make the marinade and prep the turkey. Then send the guys out to watch it on the BBQ. This keeps them out of my way in the kitchen..LOL Enjoy!
Prepare BBQ grill with lots of charcoal or wood, your choice. Soak hickory chips in water. Mix all marinade ingredients in deep glass measuring cup or equivilent. Heat in microwave just until butter is melted. Set aside and prepare turkey.
Wash turkey inside and outide with cool water. With a very sharp serrated blade knife or as I use, a hack saw I use just for my turkeys...cut alongside beast bone all the way through. Then cut down both sides of backbone and cut it completely out. I cut the backbone in half and put it in a pot of cold water with neck to simmer for stock to make the gravy and dressing.
Pat turkey halves dry and lay each half on a double layer of heavy duty foil big enough to wrap completely around turkey half and securly close after injecting. Using an injector syringe, fill and inject turkey all over about every inch, front and back, keeping marinade stirred as you go. Repeat with other turkey half.
Season outside of turkey with more BBQ seasoning, seasoning salt, pepper & cayenne. Wrap the foil around turkey to cover completely and fold seams to secure. Spread coals so turkey cooks over indirect heat, add soaked hickory chips a little at a time during cooking process. Place turkey halves on grill and poke holes all over the foil to let the smoke seep in. Turn over every 20 minutes for 1 hour and 30-50 minutes.(depending on size of turkey) pull foil back so turkey will brown the last 30 minutes. Test with an instant read thermometer to read 160-165 degrees. Remove from grill and cover with foil again to rest for 15 minutes. Carve and enjoy.
Note: You can use the same injection liquid and smoke the turkey instead of BBQ'ing it. It will take about 7-8 hrs, depending on the size of the turkey.
Last year I used Michael Simon from The Chew's method of spreading sausage (he used chorizo, I used Jimmy Dean sage sausage) under the breast skin. This added alot of flavor and kept the meat very moist.