I've been aware of the tree stand for several years. It plays a part in my opinion theory that BG had a view from a perch of the trail and/or bridge and could see who was traversing it.
I've mentioned several times that BG could have easily parked at the cemetery, checked and/or set up the crime scene, then moved to a vantage point where he could monitor the trail. For that matter, he may have done this very thing numerous times prior, but the pieces never fell together until that fateful day.
Park at cemetery, check crime scene for security, go to perch and watch. Then to the NW side of the bridge, follow the girls across, force them back over the creek to the crime scene, then right back up to the cemetery, easily driving away on rural roads.
The only issue is IF he was seen on the NW side of the trails, closer to the Freedom bridge, or known drop off spot, which sighting is a thing I question. Of course, he may have accessed that part of the trail to get a handle on the number of people milling around, prior to a forced walk back to and across the bridge, trapping the girls.
All speculation, as we just. don't. know.