Custom Orientation for Mirror/Lock/Tiling in Sculpt Mode

Right now if I want to sculpt on the chamfered face while only affecting the depth I should be able to simply lock X and Y and use the orientation of the face.

But what I instead have to do is rotate the object and align that face with the XY plane. This could get even more awkward if the origin is far away from the face I am trying to sculpt on.

It would be nice if there is a way to set a custom orientation for locking, for example by having an option there to use the current transform orientation the user has selected.

I know there are other ways to sculpt on a specific plane, especially with the example I showed, but sometimes you just need to set an absolute orientation to sculpt on that will just work.