I thought that the above approach might not work, so no worries. Of course the upward stairs will not have the same problem. Any sort of downward stair is going to be tricky and limited at the moment then, therefore would likely be a place holder.
The only option, for now, would be to create an object that sat above ground, like a dias or raised platform --with the stairs cut into it (obviously this can't be walked on, only clicked on to provide the transition).
or
Modify a wall mesh with a doorway in it.
For either option it would be handy for me to be able to import the cave wall meshes, to know what sizes to make these objects. I'm able to import the player mesh from Kalimgard's .obj file, to get relative size to the creatures. But then, it probably wouldn't work well to scale the finished object to match the environment afterward --I hope you understood that.

Let's see what work Psycho has done for the stair, I may just move onto making more architecture, if he's got further with the project.
EDITHere's a rough concept model for the downward stairs within a raised platform/dias. Definitely not to scale, it's just been modeled quickly.
