The school I helped administrating did the same quite recently. I am so glad that we don’t have to spend time with such WSUS workarounds from Microsoft.
We now manage feature updates by specifying the target Windows build via GPO.
That’s enough for our needs and works great to ensure that all computers use the same feature update and the latest of all other updates.
Luckily that’s the only place I have to deal with Microsoft / Windows at the moment.