You said you wanted to go in the summer uniform, right?
Take lots of screenshots for reference, find a sewing pattern that matches it as best you can. I'm not much of a sewer myself, so I'm not much help, sorry.
In terms of wigs, since I'm doing Shizuma as well and did a lot of research into it,
this is the one that I found to be the best, and it's what I'll be getting. It's not too expensive compared to some others and not unmanageably long, imo.
I'm going in the black uniform, otherwise I'd've provided screenshots for reference for ya. :x
Edit:
You should join in our photoshoot, we'll need to get a picture together~
![Cheesy :D](https://www.kumoricon.org/forums/Smileys/default/cheesy.gif)