Be sure to thaw the turkey fully. Remove from the fridge and let sit at room temperature for 1 hour to take the chill off before roasting.
Preheat oven to 350 degrees F. Remove giblets and neck from turkey. Pat turkey dry.
Combine the salt, brown sugar, smoked paprika, black pepper, onion powder, garlic powder, and cayenne pepper in a small bowl. Set aside 2 tablespoons. Add remaining spice blend to a food processor along with the chopped bacon and pulse 10-15 times to create a paste.
Separate turkey skin from breast by gently wriggling your fingers underneath the skin at the front and back of the turkey. Season the front and back cavities of the turkey well with salt and pepper. Stuff the cavities with some of the roughly chopped celery, apples, onions, carrots and lemon, and sprigs of fresh herbs like rosemary or thyme, then add any leftover aromatics to the bottom of your roasting pan to create a bed that will elevate the turkey out of the juices while it cooks.
Using your hands, stuff some of the spiced bacon paste under the loosened skin from the front and back of the bird, gently pressing and massaging to evenly distribute over the breasts until all of the bacon has been used.
Drizzle the outside of the turkey with the olive oil, then sprinkle with the reserved spice rub. Tie the turkey legs together with kitchen twine and tuck the wingtips under the body of the turkey. Set turkey on top of the vegetables so it doesn't touch the bottom of the roasting pan. Tent the breast area of the turkey with the foil shield before placing in the oven.
Roast for 13-15 minutes for each 1 pound of turkey until the internal temperature reaches 160 degrees F when tested with an instant read digital meat thermometer stuck into the thickest part of the breast and 170 degrees F on the thighs. The temperature will continue to rise another 5 degrees F even after the turkey is removed from the oven.
At the halfway point, remove the foil shield. I like to baste the turkey with the juices from the bottom of the pan a couple times an hour from this point, but it's not totally necessary. Continue to cook the turkey until nicely browned on the outside and the temperature reaches 165 degrees F.
Remove the finished turkey from the oven and cover it loosely with foil. Let the turkey rest for 30-45 minutes before carving to allow the juices to redistribute. The drippings and juices in the bottom of the roasting pan can be used to make turkey gravy, if desired.