Mod-PageSpeed support for multiple domains on WordPress

We are hosting hundreds of websites on multiple hosts in AWS, and are trying to correctly configure the Apache Mod-PageSpeed. The issue we have is the following: since the list of hosted websites is dynamic, whitelisting them one by one in the configuration using ModPagespeedDomain isn’t a solution.

So in our test, for now, we are using ModPagespeedDomain *. As a result, other domains are obviously failing, since the websites end up having resources like http://example.com/main.css.pagespeed.cf.eq3E2z30Fz.css, where http://example.com/main.css does exist, but the target website doesn’t have mod-pagespeed.

I have the following two ideas, but didn’t manage to make neither work:

Open for any idea / suggestion. Thank you! Charles