RE: Keeping flys off your deer.
I like to skin it and then put it in a cheesecloth game bag. I suppose you could put it in there unskinned - just never did it. Once inside, I would think a little of your pepper spray around the opening would keep out any especially clever flies. The bags are cheap and easy to carry. If you put a stick or two inside the ribs to keep the cavity opened, the air will still circulate through the cloth.