Log.Bricks: Reaction when reaches Rotation Limit ?

Greets, blokes,
I’m training myself a bit on bones and my current model already has a somehow advanced and dynamic idle state containing of randomly Eyes tracking a focus with slightly trembling eyes and the head plus torso plus both arms tracking to it as well but not as strong, while standing on slightly tottering legs.
Now what would come in handy would be that as soon as the head, which already owns a Limit Rotation Constraint so far, reaches the Constraints Limit, some sort of action would be done. (Of course I want that creature to turn around, but that’s not the point…)
Now, I actually thought I’d have to use the Logic Brick Sensor »Armature«, choose the »head« Bone, then choose the Constraint »Limit Rotation« and then…

… yeah, what then?
I thought »Rot Error ab./bel.« would be correct, but then the Sensor also expects a »Compare Value« and whatever I tried to do with the Sensor, the Actuator would not work the way I want! Either it is permanently active as if it was sensored by Always or it does not do anything at all…

Wha?! D:

Come on, guys, please! D:
How would I achieve my model to react onto reaching a Rotation Limit?
Or: How would I make it react to its head being bent in an uncomfortable angle?
I’d even accept awkward workaround ideas. ó~ò