Thanks a lot for this!
You can actually override EMouseCursor::Type UGameViewportClient::GetCursor in your own ViewportClient class.
We had one already cause of some Splitscreen stuff.
Not sure about the FSlateApplication::SynthesizeMouseMove stuff yet, but I doubt it will be a problem for us. Generally just want to hide the ■■■■ cursor when navigating UI with a Gamepad.