Bruce,
Regarding the Recca story, I believe that you have asked the question, "what was Walter Recca doing in the woods of Cle Elum on 11/24/71?"
Based on that, I thought I would mention this story from the part 72 FBI files. It was an interview with someone 5 years after the hijacking. I won't regurgitate it all here, but the general summary is as follows. This person and a few friends were going to a Methodist Church camp in Ellensburg, Wa on 11/24/71. (The Manastash Creek area is also mentioned.) Anyway, they encounter a strange man in the woods, virtually in the middle of nowhere, at approximately 11:30pm. The rest of the story unfolds regarding the man's description, that he appeared tentative and somewhat inebriated while asking them for a ride to the nearest highway. Other tidbits...a remote hunting cabin broken into, a roll of $20s.
Not sure if you or anyone from Washington state would consider Ellensburg/Manastash Creek as close enough to Cle Elum for this story to be of any interesting data point, but when I looked it up on Google maps, it seemed to be relatively close....and thus I thought I would just post it here.
I don't believe Recca was Cooper--the story sounds crazy to me, but nonetheless, here is an account of an encounter with a strange man in the woods/mountians in the Cle Elum area. I haven't circled back to the Recca story in terms of where that diner he showed up in and it's location relative to this area, but would be somewhat intriguing if it were in the vicinity.
The entire account can be found in FBI Part 72, page 205 through 208. Again, more than likely, this is nothing but because of the location, I thought I would put it out there.