Speaking as a backpacking moose hunter, here goes.....Get heavy duty elk or moose bags- Forget the cheap cheesecloth or the thrifty bags. Ideally, you should have at least 7, 14 would be better (for moose), but they are spendy. The doubling up lets you strip the bloody bags off the next day, or when you get the meat out, and put clean ones on.
You need a bag for each leg, each side of ribs, and the boned out back and neck meat, and incidental loose hamburger scraps you might have. I try to leave the leg bones in until processing, but since I'm hunting a couple miles back in, I generally bone out the back, neck, and ribs, and process this as soon as I can while the legs hang another day or 3 at home.
If you are using horses, and can quarter the elk, then you only need 4 or 5 bags (one for the neck?).
I am leaving on a backpack caribou hunt in a few days, and lately the temps have been in the 70's, so I'm in the same fix, but with a smaller animal. To help keep spoilage down and flies off, I soaked my game bags in vinegar and redried them. I'm taking a half gallon of same and a spray bottle to treat the outside of the meat with after skinning and drawing. The acid supposedly retards bacterial growth and repels flies, and helps create a crust on the meat. Once the crust is on it, flies won't lay eggs on the crusted part, but they will certainly try to get into the wet crevices of cut ends, etc.. Don't know if the acid bath works, first time I've gone this route. Heard it does tho.
As for cooling, get the animal gutted and skinned and drawn into pieces ASAP. Bag the pieces immediately to keep dirt and flies off (don't worry about the heavy bags retaining the heat- they won't much, and it's better to keep the meat clean and fly-free, than compromise this in favor of marginally quicker cooling), and hang them in the heaviest, coolest shade you can find in the vicinity. If there is a breeze, so much the better. Hang them overnight, initially, to let them cool out thoroughly before loading them unto horses or your backpack, and commencing the long-distant packing. Protect from precipitation or dew, without letting plastic or tarp contact the meat, and allow for air circulation (sometimes I lay the meat out on racks, or deadfalls for cooling, instead of hanging it, putting branches over the meat, then covering with the tarp)
If there are bears in the area, get the meat moved a couple hundred yards away from the kill site before nightfall if you can. The bears generally target the kill site/gut pile first.
If the meat is wrapped in mannies or other thermal cover during the day, unpack them and hang them each night. Always hang/place the pieces so they are not touching each other anywhere. For the "loose pieces" bag(s), open them up after the flies quit for the night(if they do) and spread the pieces out to drain/and recool. If you have a way to insulate the cooled meat first thing in the morning against the day's heat, do that too, but unwrap and recool each night.
Even with temps in the 70s or 80s, that fresh, clean, blow-less meat is good for 3 or 4 days if kept dry, and cared for as above, until it absolutely must be put into temperature controlled conditions, and/or processed. If it is getting chancy when you get out, freeze it immediately, then thaw out the pieces as you can process them, assuming you are doing your own processing.
Hope this helps. Pepper is supposed to also help keep the flies off, and so will smoke.
