The slit down the back was about 7.5". There are two layers to everything but the hood. The tricky part is flipping the dress right side out. Originally, I sewed both the bottom hem AND the sleeve hems. NOPE. Sew the bottom hem first. Flip the dress inside out. Then, pull the sleeves through the neckline and sew the inner layer to the outer layer. If you pull the back keyhole through the neckline, you can sew the right sides together for that.
I can't seem to lose the scowl / Resting Sith Face from my Imperial Officer Uniform. . . .
Don't forget to leave a slit in each side of the dress up to knee height!
Tip: Don't let your dog eat the death star plans!
If you have any questions, feel free to contact me on Facebook! I'm happy to help!