I always liked to sit at a high location and just glass the field for hours. When your sitting at a place in the field don't make fast movements or stand up. Also liked a high location for safety and you can see over the grass. A high location should give you a good ground backstop. Shooting uphill is more dangerous. I never stalked they see the movement. Because of the shape of your field you may have to move a couple times. A couple after noons at the field will give you an idea of the GH population. Your lucky the grass is short. Sometimes the dens are not in the open field. They may be just inside the tree line. Dens in the open field can usually be seen. Depended on the terrain you may want to sit in the shade of the tree line. It also makes it harder for them to see you. Looks like it may not be more than 150 yrds. for most shots so you have to be carefull about movement. Even going from laying down to sitting up they may catch the movement.
Yep, elevated is always good if you can get it. If you cant then use a tree stand. Not the best thing to precision shoot out of unless you have a rest or bar to sit the rifle on, but if you have either it works just fine.
I have killed several with my bow, but I always had to do it from a tree stand. I have never been close enough to one where he gave me time to get drawn on the ground. As above, it might seem like they have poor eyesight, but they can definitely see movement real quick.
Even with a rifle I don't remember ever killing one stalking. Tried it, seen some, but they always saw me first. One thing about woodchucks...when they freeze and stare you had better be doing the same thing!!!