Archiving a project without media

Hi all.

Probably a very simple answer to this question, but something I haven't been able to work out myself.

I currently have a library containing just one project that is taking up 100GB of storage on my external HDD.

This project is complete, so I want to archive it in case it's needed in the future.

I've reduced the library size massively by deleting the render files.

Now, I've created a new library called "Archive Library" on another external drive, then selected the original project, then File > Copy Project to Library.

I select the "Archive Library", I have not checked "include proxy media" etc, but this increases the size of my archive library to 7GB.

I only want to back up the project without any media - if I need to use the project in the future, I can import the original media again.

Is there a straightforward way of doing this?

Thanks.