admin sub-sites?

I have a site that organises all models by linking them to a project (either directly or indirectly) I would like to show essentially the whole admin site again, but below url of admin/project/1/ (ie admin/project/1/admin), restricted to the objects that have been created in project 1, and automatically linking any new object’s ‘project’ field to project 1.

I am not sure if that is clear enough, but I haven’t run into the answer and am not sure how to describe what I’m looking for. Anyone have any pointers? Is this a use case for a subclassing the admin site?