If you need to use two meatloaf pans to make the meatloaf fit comfortably in the pan with room to spare, do so.
My Aunt Libby's original recipe calls for 2 pounds ground beef but I usually use 1.3 to 1.5 pounds meat for my small family of three and adjust other ingredients accordingly. So one meatloaf pan is all I need.
Try not to substitute ground beef with turkey and use a fattier 80%-lean beef choice. True, it is not as healthy but the taste is amazing!