On cooking for a serving time, i.e. having a party/dinner at a specific time, start the cook to complete the cook early, say 4-8 hrs finished before serving time. Wrap in a couple layers of butcher paper or foil. Wrap in a couple bath towels. Place on a couple towels in a large cooler and put another towel on top. I've done this even with butts and ribs and they remain hot enough to burn your hands even after the long rest. You can put a temp probe in next to the meat if you're concerned about getting below 140°F. I've never had issues with temps dropping too much.