This past Thanksgiving, I roasted a 22 pound turkey and an 8 pound breast using my mother's toasted salt and peppercorn dry brine, which was modified from the way she used to prepare roast duck. The technique I perfected by experimenting with a small preview turkey (Link to the recipe) worked like a charm in keeping the breast temperatures below the thigh temperatures throughout the roasting process of this much larger turkey.

The 8 pound breast took 3 h to cook, as it was still partially frozen after 3-4 days in the refrigerator, but the convection oven definitely makes a difference as shown by the steeper slope of the red graph. The 22 pound turkey took 4.5 hours to cook. Cooking it upside down for the first 2/3 of cooking time worked great in preventing the breast from overcooking.

Once the turkey breast came out of the convection oven, it was used to reheat the mashed potatoes, and then the large oven was used to reheat green bean casserole, cider mashed sweet potatoes, a basket of rolls and an Oven to Table Wilton Armetale serving dish loaded with roasted brussels sprouts and cider-cinnamon glazed butternut squash. Click for make-ahead dishes.

After platters of skin, white meat and dark meat were carved from the turkey, the rest of the carcass was broken down so that the bones, along with the neck and gizzards, could fit into a 6 quart Instant Pot and an 8 quart slow cooker to be transformed into broth (See below).
The pan drippings from both pans were poured into large 4-cup gravy separators, removing several spoonfuls to flavor the wild rice dressing. A cup of water was added to deglaze each pan, the pans were warmed over a low burner flame, and a spoon used to scrape all the precious browned bits and fond off of each pan. This liquid suspension was added to the drippings in the gravy separators. After removing from the top layer the required amount of turkey fat for the gravy (Recipe in link), the remaining fat was separated from the meat juices, placed in a jar and stored in the freezer.

Wild Rice Dressing

To feed 32 people and generate enough gravy for turkey and 20 pounds of mashed potatoes, I added a Mason jar of previously frozen drippings/stock from the preview turkey to the three cups of fresh drippings. Ten tablespoons each of flour and turkey fat were cooked into a medium brown roux before the 5+ cups of deglazed drippings were added and transformed into about 2 quarts of golden-brown gravy.

After singing the our Thanksgiving prayer, we feasted on:
Chinese Szechuan peppercorn spiced roast turkey and skin (link to recipe)
Wild rice dressing with prosciutto, peas, winter mushrooms and hazelnuts
Country mashed potatoes with scallions
Party potatoes mashed with cream cheese and sour cream
Cider baked sweet potatoes 
Green bean casserole
Spinach salad with hard boiled egg and bean sprouts
Maple-cinnamon glazed butternut squash and roasted brussels sprouts with pecans and cranberries
Dinner rolls from Loafers Bread (honey white, honey whole wheat, challah, Laurel Mountain herb)
Chilled shrimp platters x 2
Charcuterie, hickory smoked cheddar, Montchevre fig and almond cheeseball, homemade bacon-cheddar coated cheeseballs, crackers, apple dip
Crudité with jalapeno-ranch dressing
Salsa & tortilla chips
And a table full of desserts including Aunt Eloisa's famous carrot cake, pumpkin pie, buckeyes, chocolate peanut butter pie, turkey cupcakes, brown butter Bourbon spice cookies and 3.5 gallons of vanilla ice cream from Any Given Sundae with homemade hot chocolate topping.

Making Turkey Stock

After adding enough water to cover the majority of the bones, the Instant Pot and slow cooker were left to transform their contents into a rich broth. The Instant Pot stock/soup program cooks for 1 h at high pressure before switching to keep warm for a natural pressure release. The meat on the bones is still very tasty with a good texture, and can be separated from the bones and used in the soup.

Meat pulled off the bones after the 1 h Instant Pot stock program

The slow cooker cooks for 6-8 h, or overnight if it is late and you will be getting up early. The meat, cartilage and skin is flavorless and rather flabby after prolonged slow cooking. Still, I made sure to carefully separate the soft parts from the bones, as the chows greatly enjoyed the bits of post-slow cooker turkey mixed into their dog food.

Before retiring for the evening, the broth from both cookers was strained from the bones, combined, and set outside overnight to cool as the outside temperature was well below 40°F. I call this the grade A stock. It is rich in flavor, aroma, and joint-friendly glucosamines. The stock cools into a nice gel, from which it is very easy to scrape off the fat the next day.

The Grade A stock made from roasted turkey bones has a silky mouthfeel and rich color and flavor

The bones from the Instant Pot can be used for one more round of stock making in the slow cooker for 8-10 h to maximize flavor extraction. After straining out the twice-extracted bones, which are then discarded after removing choice pieces of meat and tender cartilage for dog treats, I reduced this stock to 1/3 of its original volume, so it fit into two mason jars for freezing. I call this the grade B stock, as it is thinner, but find that it is still more flavorful than most store-bought versions.