Spoiliage is caused by bacteria, bacteria thrive in warm temperatures and moisture, thats why refrigeration or drying(jerky) delay spoilage. I guided a lot of hunters in Australia, where it wasn't unusual to hit 100F and we never had any meat go bad and that was from some very big animals like feral cattle, water buffalo, red stag etc.. Its best to cool the animal as soon as possible, field dress or quarter or bone it out, get the hide off if practical, keep the meat clean of any bacteria carriers like dirt, feces, hair etc.. I don't like to get the meat wet, it just makes the bacteria happy, but like on a gut shot animal, washing it out with clean water is the lesser of two evils, just don't leave it wet, dry the meat off. Hang the meat in the shade in a low cool spot or at least get it off the ground so air can circulate underneath. Dry ice has its use, but it can also be dangerous, people have died from sleeping in campers with coolers of dry ice. Also I don't want the meat frozen until AFTER its processed and packaged and dry ice can do that. If you use dry ice, I would put it in the bottom of the cooler and lay several layers of newspaper or cardboard on top and then the meat on that. Regular ice is a problem too, in that you don't want the meat to sit in a bunch of water. I don't like putting the meat in plastic either, unless its really cold and you can keep it that way. I don't bother to age deer or elk, its great if you have a way to do that, but you really need a big refrigerator with a fixed temperature. We had a walk in cooler in Australia that we could keep meat at a constant 38F and it was great for tenderizing wild cattle and buffalo, they were to tough to chew otherwise, elk and deer don't have that problem.