I echo Nick's comments. Is it possible for the landowner to see your flashlight at night? If not, I'd be ready to go in at dusk.
It almost seems, after rereading your post, that you have a visual on the buck laying dead on the other guy's property. Is this true? Shouldn't be too hard to get it out of there under the cover of darkness if this is the case. Hell, I'd drop a bunch of cow bones where the deer was and if he confronts you, tell him the coyotes must have ahd a good dinner.