I also have really long hair, all the way down to my rear, and have an issue with back carrying. So far I have tried braids and buns. My LO still manages to find the little hairs on my neck and rip them out. I am currently borrowing a wrap (along with many other carriers) from a friend and it is
The Only carrier I have been able to do the back carry in with out my LO ripping out my hair because it traps his little hands

I have been doing the rucksack carry. That is why I really want to buy a wrap of my own

Hopefully some time soon... The other carriers I have tried back carries in have been a Moby, a Mei Tie and a Chunei but I still had little hands in my hair.