(Now this is a bad example), but it's probably just like overalls, where you just have the shoulder straps going over, well, the shoulders! Plus, if you're using a wig at all(or even a long one), or maybe your hair is just naturally long, but you could probably do whatever you wanted with that back. :)
Sorry I really didn't help answer your question(and the answer to that is, no, I've looked all over for side and back views of the uniform, but fail to find any), but I hope this might help a little bit. :) Let me know if you need help with anything else, I'd be glad to be of assistance!
(no subject)
My best guess is that the back of the cosplay you are considering is fairly simple.
http://sakurasaku.deviantart.com/art/Commission-Nunnally-70519523
(Now this is a bad example), but it's probably just like overalls, where you just have the shoulder straps going over, well, the shoulders! Plus, if you're using a wig at all(or even a long one), or maybe your hair is just naturally long, but you could probably do whatever you wanted with that back. :)
Sorry I really didn't help answer your question(and the answer to that is, no, I've looked all over for side and back views of the uniform, but fail to find any), but I hope this might help a little bit. :) Let me know if you need help with anything else, I'd be glad to be of assistance!