In that case, spatchcock the turkey. That is to split the backbone portion lengthwise. You'll reduce cooking by a little less than half. Instead of the bird being say 8" high for a large turkey, it's less than half and thus heat radiates evenly. There is also no hollow area with colder temperatures requiring more cooking time. I was able to cook our turkeys quickly and without them getting dry. As I said, using heavy duty foil to cover key portions of the bird to deflect heat helps. The breasts will cook somewhat faster than the legs and thighs. Unfortunately, in a turkey, the legs and thighs do contain more tendon and hard fat that needs to render. You may end up with rich brown meat, but dry breast meat. Alternatively, you can debone the bird and use the raw bones to make a stock and store in the freezer. Contrary to popular opinion, I'd look for a bird with high chest fat and or thick skin. The more fat there is, the more it'll baste itself while its fat renders. If done correctly, you will be rewarded with taught, crispy skin that's very flavorful and has very little fat left.
Most people prefer to wet brine their turkeys or ducks, but I prefer to employ the use of a dry brine and pricking the meat under the skin. I will then rub my spice mixture generously inside and out, and the underside. I'll leave it in the refrigerator overnight and then roast the next day. This is the first year I spatchocked it after having done it with duck, chicken and Cornish hens for years. It hadn't occurred to me until I read about it on a blog a few weeks ago. It's also something I advise people to do if they plan to cook quail. Ideally a deep stoneware dish and spatchcocked quails. Preferably 6-10 depending on the size of your dish. Layer with olive oil and white onion with minced garlic. Lay quails cavity portion down. Roast just until the outside begins browning. Pull out.
Dump chopped butter, peppers, zucchini, aubergine, yellow squash, cayenne pepper to taste, small amounts of turmeric, fresh cracked black pepper, 4-6 oz of good tomato paste diluted with hot water -- feel free to add fresh tomatoes chopped roughly or if you're forced to canned San Marzano (if not, canned stewed tomato will do fine), coarse sea salt, 1-1.5 cups of good red wine, sprigs of fresh thyme and rosemary, be generous with olive oil. Cover with foil and continue cooking until meat and vegetables are done. Uncover for 10 minutes in the oven and then remove.
Enjoy.
Ideally, one shouldn't be forced to roast a turkey. It can be cooked in a myriad of ways.
