hi ken. Am enjoying your blog and barefooted hiking diary. As a fellow tail conference member, trail walker writer and a podiatrist, I would be interested in speaking with you at some point about your latest venture, as well as trail running. Btw. I often record the skin surface temp of patients' feet and have noticed that in doors with socks off, foot temps are often 15 degrees or more cooler than core body temp. The added coldness of being unshod in cold weather may help you determine a lower limit of safe outside barefoot temperatures.