Remove the backbone and flatten the turkey so it lies open.
Mix butter with lemon pepper seasoning. Gently loosen the skin from the meat with your fingers and work the mixture beneath the skin wherever you can reach.
Season the outside with kosher salt. Place the turkey on a tray with a rack and refrigerate overnight. CJ suggests two nights for a larger bird.
Slide fresh lemon slices between the skin and meat. Sprinkle additional lemon pepper seasoning over the outside, as shown in the video.
Load grill-compatible smoking pellets according to the grill instructions. CJ uses Smokin Pecan pellets. Set the smoker to 325°F (163°C). Insert temperature probes and position the turkey with adequate lid and fan clearance.
Smoke until a thermometer verifies at least 165°F (74°C) in the thickest part of the breast and innermost portions of the thigh and wing, avoiding bone. This endpoint follows USDA guidance; see the note about CJ’s video method.
Rest for approximately 20–25 minutes. Separate the legs, thighs, and wings at the joints. Remove the breast meat from the breastbone and slice.