If you can't see very far, then killing them before they smell you first is going to be tricky. If you can find an area where you can see a ways will be better than sitting in an area where you can't see 30 yards in any one direction. If they get too close without you being able to see them, then you might not have a chance to get a shot, even with a shotgun. Try to find an area where you have some clearings that give you a chance to see them coming. Even 100 yards of broken visual would be good. If you can sit near the edge of the woods where you suspect them being and if you can have the wind blowing your scent into a clearing behind you, I think you will have a chance of calling them in. Then, you and your dad sit side by side at the base of a tree, one watching into the woods where you beleive them to be, and the other needs to keep an eye toward the open field, especially for some thing that may come right down the edge of the woods along the open field!
Like I said, I think you need to get in thier comfort zone, BUT if you can't see them coming then chances are they will come and go without you getting a shot off, which would defeat the purpose! SO, don't take a chance of calling them in if you can't see well. Maybe even concider standing up at the base of a tree, if that will give you a better vision through thick under growth! Problem with standing up is holding your gun at the ready, which you will want to do, because in the close quarters, getting a gun up once they are in range will be very hard to do without spooking them!
It's nice to call them in the open fields and be able to watch them come, we are spoiled in the open prairies, BUT if you want to kill them in the thick stuff, ya might have to go in and get'em!