Great thread TZ, I had a go at this the other day, I modded another hammock so aesthetics in the footbox area are somewhat compromised but it works fine.
I made mine 126" finished length and at 6'3" it is still a little short for me, it was definitely better for my sister (6') but still coulda been a bit longer. My friend who is 5'10" is going to try it soon, it will probably be fine for him.
I missed the post where you say you now recommend a 15" diagonal on the head end on the first read so mine is 20". Does it make that much of a difference?
I am ordering more fabric to play with come payday so I will get to play with this design again.