Alternative or design pattern to avoid InternalsVisibleTo?

Context:

I have a Unity project in which I have numerous internal types which in turn are used by other types such as editors.

As project is growing up, it starts to be a little difficult to find yourself in all this, so one would use assembly definitions which are nothing more that the equivalent of .csproj files.

So that's pretty cool since you can finally split your work into separate projects, but now comes another problem: how to access those internal types?

The InternalsVisibleTo comes in handy in this case but the downside is that, everything non-public gets now exposed, adding a bit more to the confusion.

Question:

What alternative approach or design pattern for doing without InternalsVisibleTo?