One thing that might help (if it goes to the sort of angles you're looking for) is the Vectric chamfer plug-in/widget or whatever they call it*. It's meant to be able to cut chamfers of any arbitrary angle using e.g. a ball nose cutter, you can adjust the smoothness apparently by setting the step-over. I'd be interested to know how you get on with it as I have a project coming up which is going to need a lot of strange angles cutting.

* https://gadgets.vectric.com/V8/chamfer.html