aa, lickity split find out who posted that sign and ask to hunt that area. Do that and the sign will not matter right? Get up, find the person, get permission, take your detector and your "Warden", and "WEAR THAT SITE OUT."
Brother, I discovered through research about two years ago a site in the middle of a bean field in Tennessee where ole Forrest camped for one night before a battle in 1863. I was leaving for Texas so I left getting permission in the capable hands of my buddy, but new to detecting childhood friend. Did I say capable hands? HE NEVER DID IT in one year!! The first thing I did the next summer (last June) was go to the closest house to that property and ask who owned it. The fellow was a really nice guy and told me where the owner lived. I went over with a pecan pie my Mama had made, said hello, explained what I wanted to do in his bean field two miles away and guess what? He told me not only to go ahead but that he would make sure to tell neighbors to leave me alone when ever they saw me!!
Now when I go home at the top of July this year you know I am going to kill that sites. The finds have not been great because it was an overnight encampment, a couple of artillery fuses and a really roughed up bullseye canteen, but all I had to do was ask! (Yeah with a pecan pie. Mama did not raise a fool and I guarantee Mr White the property owner gets a nice bottle of Mexican hot sauce given to him this year.) My buddie did not even bother to do this 10 min job close to home. He could have been detecting the site all year.
The point is ASK. The worst is that they say no and your no better off, but they might just say yes!! Good Luck!
Again i said yes and the Warden frowned sayin NO . As we drove away i thought ok she was right but next time she is stayin home. 
