I had almost the same question - and went in some other direction:

https://github.com/mabels/ovn-fabric --- there are some docs about why I got to that. And OVS should also utilize the hardware offloading of your mono router.

The current main is in a state between a works-for-me proof of concept deployed in production on two instances --- and the more generalized version.

If you want to try it -- I'm happy to help.