In summer I'll find a creek bed or river and wet the cases before putting meat in if one is close by. Give it a rinse first, put meat in, and find a shady and cool place to hang for 30 minutes. My theory is that helps cool the meat quicker. No science to prove it but if your wet and stand in the wind it cools your skin down so thought the same would apply.
When you pack it out in your day bag and carry it the meat will warm up from heat on your back. Stop frequently if it is a long walk and hang out for another 30 minutes.
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