There's probably a more efficient way, but that's what I had in mind.
I know we can modify the Terrain's Height with triggers, so if you set regions for possible walls and randomly elevate the Terrain, you'd be able to use Mech Combat's Slope system to prevent units from passing on these "walls".
Doodads:
All I can think of is, for example, to place multiple sets of doodads in the same room and based on a random integer picked up the editor, delete all the sets except the one that was selected.
Could do the same with a forest to change its basic configuration.
... or maybe is there a "Create Doodad" trigger I missed?
This is mainly just a rough draw to incite people at sharing any ideas or creating a concept map.
None.