The image I attached shows the trail which leads from the NW approach to MHB, down to the general area of the CS less than 1/4 mile walk from there. I believe the killer used this trail or perhaps another, more challenging trail, to get out of the gorge after leaving the CS.
I was surprised to see how easy it is to access this trail, it is on the M family property. There are videos on YT showing how easy it is to navigate this trail, in fact in February it would have been downright easy, due to the lack of vegetation.
I'll go along with what LE has indicated for some time now, that BG used the main trail to get back to a vehicle at the abandoned CPS building. The traffic on the trail happens in what I call "bursts", and BG had to know this. I noticed it when I was there in October, one minute you're around 20 other people on the trail, next minute you're alone.
He would have had a little bit of concealment for a vehicle there, plus the traffic is sparse on C.R. 300 to begin with. Versus parking on the other side of IN 25, and walking across Freedom Bridge like most people do.
I hope this helps, I try to use some logic and a general sense that BG had to conserve energy and make his movements as short as possible that day.
If BG did indeed get back on to the main trail near to the bridge, it would have taken him mere minutes to get back to the building, maybe 12 minutes.
JMO