Bring large pot of water to a boil with Cajun/seafood boil seasoning, salt, garlic, lemon, onion, and optional hot sauce or cayenne. Add baby potatoes first and cook for about 10 15 minutes, then add corn on the cob and sliced smoked sausage and cook another 5 minutes. Add the cleaned live crawfish, cover, and boil for about 3 5 minutes until bright red, then turn off the heat and let everything soak in the seasoned water for 10 15 minutes for more flavor. Drain well, transfer the crawfish, corn, potatoes, and sausage to a large bowl or tray, and toss with melted butter, garlic, Cajun seasoning, lemon juice, and parsley. Serve hot with extra lemon and melted garlic butter for dipping.