Okay, i don’t understand what you’re going to do with vertex hook in your scene. And unfortunately, i cannot reproduce my first test with your blend using armature (Sorry, i should’ve saved that test file). I was able to get ‘vertex hook’ like behaviour, to one of the bone in your armature. Now when i tried it again, the plane is completely scaled up.
So, what you’re going to do with this vertex hook exactly? In my understanding, this work around suppose to use Copy Location constraints, and i don’t see any of it in your scene. I see only IK constraints.
Also, AFAIK you should avoid IK constraints whenever possible. IK is not a good idea for most game engine if not all. In a big scene, it can hurt BGE’s performance really badly.