Website with flat taxonomy (IA)

I’m attempting to analyse traffic for a site with a flat taxonomy and no identifying relationship between the content.

Different content types that are all part of the same subsite area are served in their respective content type folders, not via a URL that is relative to the subsite the user is located at.

The site owner isn’t keen on changing the site hierarchy or enabling path alias for each content to take a subsite variable into the URL. I don’t have a parameter that I could use in a search and replace filter, to construct logical paths either.

Any ideas? Without being able to filter in/out pages due to a URL structure, how else can I achieve this.

The site is huge, so not a question of manually making changes via post-processing a Piwik extract.

I can only think of using a custom dimension to include a new name:value, for example subsite=siteA. This would require dev work, which the owner isn’t keen on doing!

Thoughts would be greatly welcome from this community.