Game bags for elk hunting in September

[Adam]

I'm looking for a recommendation from someone with experience on what kind of game bag is best for a September elk hunt in Colorado. Do I go with the cheesecloth style (they're cheap and I don't think they're the ticket, but I've never done this before), heavy duty canvas, or these: http://www.pristineventures.com/products_gameBags.html

I'm looking for something to cool the meat down and protect it from bugs, that's durable enough to hang from a tree and hold up on a pack frame getting carried out.

Any help would be much appreciated! Thanks!

Adam