Tom,
I don't think it has anything to do with the levelers. However, I think it is part of a system for leveling side to side when one first pulls or backs into a site. There is a device that sits remotely in the truck cab, so if the driver can see he's not quite level (side to side), before using the level up or other stabilizers, he can use blocks under the wheels or whatever.
The device that sits remotely in the truck has a visor clip for placing it on the sun visors. I guess its a kind of fancy-smancy level in the truck instead of one being on the nose of the trailer that can be viewed through the rear view mirror.
Pictures of the remote device are below. Note also that the model number on the remote display is KC-0715.
Terry