I read the section in here on tunings with interest. For information, my guitar is a Harmony Sovereign, american make that I bought in 67 in London. It was customary in those days to fiddle a lot with tunings and to ADD strings. Mostly I played with 7 but sometimes 8 strings. My tunings though were always "Open". Nicks will be worth some experimentation. I first picked up open tunings and extra strings from a guy called Dave Puffer, an american who was playing in Brisbane 65/66 (Hiya Dave! Are you still keeping our birthday?). In my London days I was in the era and area of Alexis Korner, Long John Baldry and Roy Harper. That was when rock was going ballistic and people still wore flowers in their hair!!! hahahahahaha
If you couldn't tune your axe you tuned your head - what am I saying.