In 1915, with the risk of US involvement in WW1 looming, Gen Leonard Wood organized a summer camp at Plattsburgh, NY, to provide military training for civilian men at their own expense. What was this experience like for participants?

I can't answer your question but I can point you to who can. A very knowledgeable local history buff. I'll PM you his company's info.

Also, the old barracks from that is apparently the oldest built US military building still standing. For years it was abandoned. Now it's a brewery, recent history of the last couple years.