The unsigned and undated Note to Marina that doesn't even mention Walker is worthless as evidence
The confession to Marina isn't worthless but it should not be taken to heart in the absence of corroborating evidence. Like for example, did she tell anyone about it before her husband was killed? Did she keep a diary. Her word alone isn't enough given her credibility problems.
The other problem I have is no one seems to be able to explain how Oswald traveled across town and back with a rifle without being noticed. There's also conflicting stories between Marina and George DM about whether he came home with the rifle the same night or if he buried it near Walker's house and picked it up a few days later.
The unsigned, undated note is evidence Saint Patsy was worried about being arrested for some act, no ? That is, unless you think the note is a forgery, written by someone else, or composed after the Walker shooting.
Yeah, it's possible Marina's story regarding the confession is fabricated but as you say, it's not worthless.
As far as how Saint Patsy got across town with a rifle without being noticed, could have been done a million ways. A passenger sitting on a bus with a rolled up blanket on his lap, for example.
As I said earlier, I think there's more than sufficient evidence to say 'he likely did it'.
Photo, note, admission to wife, works for me.