Storing private config files in .git directory?

Our git client (lazygit) has a need to store per-repo config files that override the global one, much like git itself. The easiest way to do that is to store those in a .git/lazygit.cfg file, and I'm wondering if there's any reason why this is a bad idea?

Another alternative would be to store the config values in .git/config (that's the path taken by git gui, for example), but since our config file format is yaml, this would require translation. It would be trivial for scalar values such as int or string, but I'm not sure how well this would work for more complex settings like lists of objects.

Any thoughts?