As for the tie, if a guy is willing to take someone else's money, he would probably take someone else's clothes also. I think Cooper may have done a dry-run or two, and could have easily stolen someone else's suitcase from an airport, automobile or hotel.
When you're six feet tall, it's really hard finding the right size clothing to steal.
I'm trying to think of anytime I heard of a criminal stealing someone's clothes in order to perform a robbery... and I'm coming up blank. This has to be the least likely explanation for the evidence on Cooper's tie.
Interpretation of the clothing has always been biased - lite clothing ~ he died from exposure.
His choice of clothing may have been quite intentional. Planned to spend little time under a parachute. Bailed near civilisation. Nobody knows what resources he may have had waiting. His manner of dress, his time and place of bailing, suggests to me he was dressed appropriately and someone with a concrete plan and resources waiting.
His is a very simple plan and he seems totally plan-oriented, to me. His plan is an escape plan first. He even tells Tina he doesn't really care about the money so keeping the money is secondary to his primary goal which is to escape. He doesn't even seem concerned about leaving evidence behind on the plane! It's an all-or-nothing plan with escape the primary goal, with or without the money. And
that may be the reason he is never found! But some of his money was found...
Cooper is a goal oriented person who can focus (is used to focusing and carrying out tactical plans). His tie is merely part of his plan to help him accomplish a goal, to the extent of his knowledge and skills. How is he supposed to know that skin cells will yield dna - that kind of knowledge isn't even in his catalog of life knowledge. Making tactical attack plans is in his repertoire, and the simpler the better!
This guy was a tactical thinker with tactical experience. He keeps himself and everyone else focused and on-task right up to his leaving. The Transcripts do not convey but half of the conversations-communications Cooper made with Tina and the pilots right up to his leaving. 8:05 was not his last communication with the pilots, as the Transcripts and Rataczak report. He told Tina several times that the money was not that important to him (his primary goal). His primary mission was exorcising a personal grudge though hijacking a commercial airline and penetrating civilian and military security systems. We know part of his focus was McChord AFB. He expected the chutes to come from McChord which shows he had an awareness of how the military could play into this scenario. In my opinion he waited to jump until he was in a kind of 'transition zone' where he knew the plane would be handed off ...
The whole thing is a tactical mission as I see it. Performed by a person with some tactical training...
His choice of that aircraft and that particular flight (recently added) are all tactical. (those facts and conditions offer a tactical advantage). His choice of where to bail is tactical also, imho.
The whole thing is tactical from beginning to end imho. (McCoy will follow Cooper and McCoy is active Ntl Guard!)