andrade1812, I like your thinking chum.
I don't think Cooper landed in the Columbia but I keep thinking it's a possibility that he left by the Columbia. That briefcase went somewhere and to me the only secure place for a wind blast exit is in that bag, tied to his midsection, hanging on to it with both hands (non-steerable chute) for dear life. That money is the most important thing to you. It's all about the money! So space had to be made for that briefcase. You put money into that briefcase and you make some space for that briefcase in the bag. How much money? I dunno, how about $5800 worth as a guess. Cooper wanted a backpack of money, he got a canvas bag, it's fact he made a handle on it. That sounds like he meant carry not bury. The only way that $5800 got to the bar is it was put there.
I think Mitchell is a really valid witness. You read his story and he's all like his hair was so black, like too black, in fact so odd that it could've been a toupee, unlikely but dyed? Cooper looked like a dweeb to him, there was something off with his shoes or socks. (What kind of legit businessman wears a dark topcoat, dark suit, dark tie and brown shoes?)
Our man Cooper is so crazy about not leaving his notes, etc that he goes and leaves a tie! The only reason he would take that tie off to me is that it's in his way, like hanging down when he's cutting the chute cords. Maybe he puts on the chute, with an "x" harness across the chest which if his tie was on, it would be as secure as all Hell. In every book/movie/picture someone does to mimic Coooper's jump, that tie is on. Why? Because it's instinct. It's secure. It's part of the businessman M.O. I think Cooper wanted those stairs down to either bail if he was rushed by anyone in the crew or needed them down so he could rush out at the area he wanted to get into somewhere. He wanted to be able to go at a split decision. To me that tie came off pre-harness and in the panic of the stairs, getting out in the area he wanted he said "fuck it" and bailed.