how to create a outline with openings

example snap

It is not an elegant solution, but at some point when you are snapping points on the perimeter, you can snap an interior point and create the points that define the material to be removed. When you are back to the first interior point, snap back to exterior points again. There will be a shared edge, but this is not obvious when the fill is on.

Yes, subsequently we used that approach with dummy split lines to create hollow regions.