I want to suggest this possibility:
change the definition of a node in this way:
climbable = 0: this node is not climbable
climbable = 1: this node is climbable very slowly
climbable = 2: this node is climbable faster.
etc...
so it would be possible to make climbable very slowly even the rocky walls.
I do not think something unlikely, because climbing is a sport.
Also those unwilling to climb the walls should just leave things as they are.
I do not know if this feature is implemented, thanks anyway for your attention.