Yes, as I mentioned above pythonPackageExtensions seems to be working well.
Thanks for adding the bit about disabled – I certainly find these highly builder-specific options / arguments really difficult to discover / guess (relevant: How to search nixpkgs by e.g. `buildInputs`? - #6 by n8henrie). I’ve been brainstorming how best to go through all of nixpkgs and find all examples of a specific term (e.g. pythonPackagesExtensions) and then present the user with the attrset keys and values that are used most frequently, not deeply resolved / evaluated, sorted by frequency, with links to source. I think this would be really helpful / instructional for new users.