How do you correctly hyphenate prefixes to already separated words?

Specifically, Co-Project leader is what I'm confused about. For reference, project leader would be written as separated words without any hyphen, obviously. However, once you have a vice project leader, which we mark with a "Co" prefix in our company, I'm suddenly unsure how to properly write it down.

There are really only four combinations that make any sense to me, but they all seem off:

• Co project leader feels oddly detached
• Co-project-leader suddenly introduces a hyphen where project leader didn't have one
• Co-project leader would make it seem like the Co is talking about the project, not the leader
• Co-projectleader suddenly connects the words, equally dumb

I'm so lost here.

EDIT: I know Co-founder is an acceptable way to write it. However, it's a different case here because "project leader" consists of two words, not just one as it is the case with "founder". That's why I was asking.

What you need there is an en dash, not a hyphen.

To quote from Grammarly.com:

En dashes, which are about the width of an upper-case N, are often mistaken for hyphens. But, traditionally, en dashes function as a kind of super hyphen. They’re meant to give you a little extra glue when you have a compound modifier that includes a multi-word element that can’t easily be hyphenated. For example, the phrase Elvis Presley–style dance moves uses an en dash because Elvis-Presley-style dance moves is awkward; “Elvis Presley” isn’t a compound modifier, so hyphenating it looks odd.

The Chicago Manual of Style (14th edition) gives similar advice:

5.117 The en dash is also used in place of a hyphen in a compound adjective when one of the elements of the adjective is an open compound (such as New York) or when two or more of the elements are hyphenated compounds:

  New York–London flight
  post–Civil War period
  quasi-public–quasi-judicial body

So, you can write "Co–Project Leader" instead of "Co-Project Leader".

(Grammarly does also warn that not everyone will notice or understand the difference between the en dash and the hyphen, so you may also consider trying to reword it if possible.)