get a good headlamp and shimmy up that tree at 0'dark. Except that you're hunting a hay field, so you'll blow everything out. Can you set up on a trail leading out of the hayfield? set back 1/4 or 1/2 mile back if you can and catch them leaving the field to a bedding area. If you set up at the edge of the field all you'll hear is snorts and see nothing at first light.
don't forget your safety harness, and by all means practice at home or close by. I climbed up half the trees in my front yard when I first unwrapped my new summit climber

edit: Oh and most guys have their climbing trees already prepped ahead of time, limbs cleared and shooting lanes created well before the season. Trying to find a suitable tree in the dark sucks.