Where's it at? Maybe I can come out a prehunt it an afternoon to help you out?
If its that close to your house and it appears to be a perfect funnel, I wouldn't worry about lack of sign. Give it a shot and see what comes of it.
Good luck.
BTW, you hunt Six Flags yet? I talked to my friend who works there and he's heard of some real whoppers seekin refuge back there.