I have no doubt that hanging squirrel will dry it out, but aging a big game animal covered to keep moisture in and aging a squirrel in water are two different things.

I'm not being intentionally argumentative, but aging, tenderizing, brining, and marinating are scientific processes, of which, many (unscientific) myths exists. I am unfamiliar with the science behind aging in (plain) water. What happens during these 4 days and what is superior about it compared to brining?
It doesn't have to be fun to be fun.

Wild & crazy, can't be stopped. Only the strong will survive.

Keep your knife sharp and your skillet greasy.