I've read and followed the directions to hang in a cooler (not outside) for 14 days. Some of the best steaks I've ever had. Only difference between hide on or off, is that with it off the outside of the venison (or other meat) will take on a very thin dry looking layer. Which isn't a problem.

Don't age outside. In most places in the lower 48 the temps swing between day and night. Since you don't want any meats to sit in 40 degree temps, it isn't hard to image that if it won't freeze at night, it'll probably reach 40 during the day. You wouldn't buy a fine steak from the butcher and freeze it, then thaw it, then refreeze it, then thaw it... and so on, because you'd ruin the steak. Hanging a deer outside in most cases will do the same to the venison.
"hey, this tastes gamey..."