> Must be followers of Chicago Manual of Style (and not AP Stylebook.)

You know, there are more than two possible choices. I scorn to subject myself to any style guide for my personal writing… let alone an American one. People used em-dash-sans-space long before CMOS was dreamed up.

I sha’n’t follow all the older traditions I find, but I do frequently favour them.

https://fr.wikipedia.org/wiki/Tiret has a lot of options for you :)