Turning off undo for sun position

Hey users of Rhino

Does anyone know of a way to stop Rhino recording the sun position in the undo command, similar to the (Record undo in Render Settings) in the Brazil Options.
The only way I can find is a long way with Undo Multiple.
I am needing to move the sun around the object a lot whilst turning on and off layers and hiding objects. Is there a way to record a position in time?

Regard Jahn