RE: Bowhunting the edge of fields?
From my expiriences the edge of Agriculture fields are great for Doe and Young Bucks at anytime. The big Boys tend to stay away from viewable fields (via road) until a reasonable amount of darkness insures they won't be seen.
Of course throw in the Rut and you can hunt where the does will be..some big boys are more likely to slip up at that point.
My $.02