It sounds like you might have a feeding and bedding area going on. So all you can do is make more trips out there and find the route they take. Then you have to decide if you want to ambush them along the way.

The problem with a real thick area is you often need shooting lanes or you need to be up over the thicket it self.

I personally would try to get out there and walk the area, learn their trails, and also if possible take some camo clothes and just go out with binoculars and sit on the edges of the field and watch to see where they come out from. This will all give you a much better idea of stand placement.

For instance, the thickets I hunt are on the edges of a cedar, alder, black ash bog. You can walk in there but the ground is very wet. The deer also walk through there all the time but I discovered an area where they like to walk along the edge of the higher ground out of the thicket. So I placed a tree stand in that area and ambush them as they wander out of the marsh at night. It makes for low light tuff shooting, but at least I see deer, and the shots are close..