I packed a bull out last year solo, on a November rifle hunt. I trained all year for it. My strategy was lighter loads and more trips...my training was more focused on endurance than strength. Know your limitations for both weight and distance.
My legs were cooked by sunset on the first day, which was a good excuse to not pack out any loads in the dark. I still had 2 loads of meat, the head/cape, and my camp to pack out the next day.
It will be exhausting no matter what, but very rewarding when you reach the truck with the last load. Remember to stay hydrated and keep the calories coming in...same idea as any endurance event. Keep the meat in the shade too, even if temps are favorable.
It is definitely a worthy goal to train hard for. Good luck!