My sides hurt from laughing so hard! You guys are hilarious! Seriously though, do be cautious; is it possible for you to keep a Polaroid camera wuth you at the barn? If she was tresspassing you could get photos on the spot as evidence, and keep them with documentation of anything else she pulls. If things get worse your BO could always slip the mail carrier a few bucks to"accidentally lose" her mortgage payments-she'd have to move! (KIDDING! Don't do anything illegal!!) :)
Maybe that's it! Keep a camera, and anytime she's on the property, snap some pictures of her... That might freak her out
enough to keep her a distance away!