Low and slow. Keep your heat between 250-300. Make a paste of 1/2 pound of butter and spices (dried onions, garlic powder, sage, salt and pepper) and smear both cavities and under the skin with it. The skin will pull away from the carcass, pack the butter paste in there. Put chunks of onion, oranges, and apples in both cavities. Place turkey in a pan (a pan you don’t mind ruined, I use an old cookie sheet with raised edges and line it with heavy foil). Once on the grill I add chicken broth to the pan and tent the entire bird with heavy foil. Make sure foil is tented over bird not touching skin. Watch your heat, you want to cook it slow to almost 165 but not quite. When finished remove tent to brown if it need it, then remove from fire and let the bird rest 20 minutes before cutting. It should just about fall off the bone. Toss the fruit and onion chunks.
This is the only way I’ll do a turkey anymore. It’s soooooo good.