Specifying Project.toml when starting Julia repository with binder

I want to set up some tutorials with mybinder. But my .ipynb and .toml files are not in the root of my repository.
Is there any possibility to start binder with a specified Project.toml from a subdirectory to avoid installing too many packages?

I already activated the right project manually in the notebook by running

using Pkg

But this takes too much time because first all not needed packages from the Project.toml in the root are added.
I just found some older answers to this in here but no perfect solution.