Ok sorry i wasnt able to respond to this, no your thinking to over the top mate, all you have to do is a set material brush
Video Game developers have been faking everything for ages.
the = part for condition needs to be the item or player that touches the item you want to change and then the material can be what ever you want. then destroy the trigger box component after all of it. Then you have a block that can change if you hit it and not be affected again.