Forget about being efficient for this single slaughter. Kill the animal and bleed it. Immediately hoist it by the upper jaw over a limb, rafter or any other structure using a rope or chain and a vehicle. Wash the hog with buckets of water and a stick broom while the body heat remains. Cut off the feet with a handsaw, Remove the shoulders and the hams while it hangs. Remove the loins. All that is needed is a sharp knife. Take all this in the house and leave the animal hanging. Let the rest freeze. Work up the meat in the house where it is warm. You can later go back and salvage whatever you want from the carcass. Where the idea came from that you have to gut an animal I do not know. If you want organ meat just cut into the cavity and get what you want leaving the rest. Yes, you are going to waste some of the meat but you will have rendered the more desirable cuts and it was free. Scavengers have to live also, just share the bounty. This effort will take less than 30 minutes outside.