Give stairs their own cut plane setting separate from the project cut plane to easily control the location of the break line. Plan regions work, unless you also need to control the cut height of walls next to said stairs to show slopes or openings, etc. Two separate plan regions cannot exist in the same space to get the two different cut planes required to show all necessary information in a floor plan view.
Default could still be project cut plane, with ability to enter override height, or even just a grip to slide the break line up / down the stairs.
