I only recently became aware of this case, say within the last year. Some of the details I find interesting, and they can be put together to try to profile this guy with regards to occupation(s) and other factors.
Footwear has been mentioned, both in written accounts and in documentaries. High tops like Converse/Cons, if I remember correctly, and in early cases it's been mentioned he wore these:
https://www.hessenantique.com/Vietnam_Style_GI_Jungle_Boots_p/rc5080.htm
I wore these in the Marine Corps in the 90's. They were standard issue for the Coast Guard, Marines, Army, Navy, and Air Force, from the 60's and up until the early 2000's. As anyone will tell you about hard soled military boots, there is a break-in period for them, you have to wear them often, and walk some decent distances, in order to break them in. So if indeed EAR/ONS wore them, then the question has to be asked where he got them. Surplus? On McClellan AFB? ???
McClellan appears to have been a busy base during most of the Cold War, both for the Air Force and the Coast Guard. Some of the work on the base would have required a lot of civilian contractors, for aircraft maintenance, repair, and refurbishment purposes.
Just thinking out loud, here. If early on he used Cons and jungle boots as footwear, that fact alone shows planning as both would have been common in the 70's.