We hunted the early coastal "A Zone" in California which opened in early August, always hot and often with daytime temps exceeding 100 degrees. Hide off and gutted right away, into a first quality deer bag, and hang in the shade for 30 minutes or so. We used "ice jugs", gallon milk jugs, filled with water and frozen. Four or so ice jugs, in garbage bags so they won't leak, in the cavity. Whole thing wrapped in a tarp and stuffed into an old sleeping bag. When I got a bit older and had the funds, the sleeping bag and tarp were replaced with a mega ice chest. Now these coastal bucks are quite small, usually under 100 pounds so they cooled a lot quicker than that 200 pound whitetail. But we never lost one to spoilage. A butcher who specialized in processing game told me I had a max of 6 hours to get the meat cooled to the core to avoid the onset of spoilage.