I guess you could ask your hairdresser to cut the back first and then cut the sides when it's pinned back.
It might look a little odd while it's all down, but it might be worth it to get the look you really want for going out.
p.s. I've never done this!!!
Hair Type: Fine, 3a
Cond/LI: MOP Mixed Greens
Styler: IGA Gel
Overall: Just likes a bit of TLC