The other thing you might do is contact the WBCCI chapter that operates in the Riverside CA area. I'm not sure which one that would be but you can get that from WBCCI in Jackson Centre Ohio. They probably have members who would recall the folks you're asking about and/or they still may be members. Also if the club took part in that expedition, they may have photos, films, diaries etc of the trip. If it was a WBCCI caravan, then maybe WBCCI would have records, diaries, pictures etc.
Good luck. Sounds like an interesting project.
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