I have the corpse ramp thing sorted out.
If a zombie is standing next to a wall, and another zombie is trying to get onto the wall, the zombie next to the wall can be “trampled”, which turns them into a corpse-like item on the ground.
Then a relaed feature would sum the volume of all non fragile items in a tile and if it volume is higher than some threshold (1,500 L or so?) then that tile would count as a ramp.