As has already been discussed, it's impossible for RA to have been on the bridge when Trail Woman saw him, and then have headed back on the trail to a bench without seeing L and A, since we know Trail Woman saw them on her way back while RA was still on the bridge. This is not a lot of distance that we're talking. RA had to have left the north end of the bridge shortly after Trail Woman was gone and waited around hidden until the girls were halfway across the bridge. Or, he was on the bridge and they passed him, but he left and hid at the north end before L took her first photo. Or, he had walked to the south end and was hidden from her second photo, then did the whole u-turn scenario. Or, possibly, the girls and RA did see each other on the trail after Trail Woman passed, but before the girls got to the bridge. The latter could explain why L began filming him...because he had already come from the bridge, so why was he walking back?