There’s something in here that always makes me struggle with the idea of the film being a hoax:

The subject leaves footprints, that were cast and the track line was examined by others who returned to the film site a few days after it was allegedly shot. The patty footprints are, to my understanding, pretty damn good, and show evidence of flexion and foot movement.

If the film is a hoax, we have to believe that not only is it a guy in a huge, bulky costume, but he’s also wearing fake feet. He then walks fluidly and without a stumble or trip on the first take of the film, as, as you noted, it was the last thing shot on their last reel of film. Theoretically they could have practiced a few times to make sure they had everything set up, the guy in the suit knew his path, and wasn’t going to accidentally trip on any roots or stumps or anything, but they clearly didn’t do it at the film site as Patty’s footprints are the only ones there as examined by third party investigators after it was shot.

In my mind, it’s a huge risk to waste your last reel of film on a guy who you also need to leave footprints, wearing fake feet, walking across terrain he hasn’t practiced on so could easily stumble, trip or somehow otherwise screw up the take. And if Bob Gilmin wasn’t in on it, then it’s even more or a problem because now you’ve revealed your hoax to him.

Also, assuming Gimlin wasn’t in on it, how did the hoaxer get out of that remote area? He goes and hides in the bushes for a while and gets a ride out? Doesn’t sound likely, especially after hearing that it was a bit of a treacherous drive out for Patterson and Gimlin..

I think my main point is that what an extra amount of effort to not only fake the film, but also the footprints at the same time. Seems really difficult and so much extra complexity to pull off.