How long should you cook a whole rump 5.5kgs on a rotisserie barbecue?

For a 5.5 kg whole rump cooked on a rotisserie barbecue, you should aim for approximately 1.5 to 2 hours of cooking time, depending on your desired level of doneness. It's best to cook it at a medium heat, around 180-200°C (350-400°F). Use a meat thermometer to check for an internal temperature of about 57-60°C (135-140°F) for medium-rare. Let it rest for at least 15-20 minutes before carving to retain its juices.