If you have to drag him any distance at all, don't split him from stem to stern. Only make a cut big enough to roll out the guts below the rib cage. This keeps out lots of grass and leaves. As soon as you get him to the truck take him to the nearest water faucet and finish splitting the deer removing heart/lungs/liver and wash grass and leaves and blood out thoroughly(best if you can hang him up). This cools him out and makes butchering alot nicer. If you are in a warm climate you can add two bags of ice in the chest cavity. Then go check him in.