Just field dressing the deer immediately will begin the cooling process. If you're dead set on taking the entire deer home, I'd field dress it and shove a few bags of ice in the cavity for the ride home. But, why take the deer all the way home? I hunted the California A zone for years and have been hunting Hawaii for the past six years. I've killed more deer in warm/hot weather than cool. I'm almost always boning the deer out within a few hours vs. field dressing/skinning/butchering. It's not hard to get every once of edible meat off a deer in an hour.
Once you've removed all the meat, put it in a cooler with ice and you're good for days. I usually lay my meat on top of the ice to prevent "bleaching" but in fact the ice doesn't hurt the meat at all. I've used several brands of meat bags but an old cotton pillow case works just as well. Either way, heavy duty commercial meat bags and pillow cases can be washed and re-used.
