I've done something like that some years ago to ensure that the tracking we were using on our website worked even if a user had an AdBlock. (it wasn't a tracker as in ad tracker, but a tracker nontheless)

It was fairly trivial: instead of asking for the tracking script directly I put a small service of ours in front of it, so our website asked for foo.mycompany.com/stats.js that fetched the correct script and changed all URLs inside of it from mycomp.mytrack.com to foo.mycompany.com. Our service than acted as a proxy to mycomp.mytrack.com.

A simple solution that worked out for a while, lost by now, in a server, somewhere in Ireland...