Yes, custom fields will surely come into play here, but also thinking about what your project sections are, and other factors.
Here’s one related solution that may or may not apply to you:
At first glance, I didn’t notice a relevant Asana-supplied project template to use as a starting point, though maybe I missed it.
I’m not sure we can glean the full set of requirements and their nuances in a forum exchange. I usually prefer to work directly with clients to make sure the solution is appropriate. But I also created a workshop, along with Asana’s great customer education team, to provide all the most key help I could in a general framework for how to address all such workflow design questions. You’ll find it here: