fate..you have good hair at the back there and the purple line looks to me as if it`s sitting just under the occipital bone there which is the correct place to have your perimeter. If you keep that bit of hair there [from where the edge /perimeter will sit] it will give a really good visual effect whenever you incline your head forward and down ..... a casual observer wouldn`t notice a thing. I`ll mark a few suggestions for you shortly.....also, it`s better to have the edge not sitting directly onto the ear ..you have to allow a little gap there for styling etc. otherwise the hair even though it will be relatively short, will be covering the ears ...probably wouldn`t really feel too comfortable either.... I pondered on that area and how to `approach`it for quite a while, and I may [on a future order] make a new template to allow for an even bigger gap between the perimeter and the point there where the ear meets the head.... as you can imagine..if/when hair is cut short there, it can feel like little needles sticking into the skin of the ears, and be annoying......also bear in mind, that while very straight lines and right-angles on a system perimeter can look a bit odd, a very curvy one can be problematic if you want to use tapes for bonding ,as they obviously come in rolls and have straight edges, so the more curves you have in a particular area, the more likely you are to have to use glue always for practical reasons....just something to factor-in to your plans!
I`ll post again later....cheers, Paul.