It's hard to say without knowing exactly what your procedure is.
You would typically always want to zero your tool every time.
You could write or modify a macro to automate it.
What you would probably want to do is permanently mount your touch plate somewhere out of the way.
Surface your spoilboard, and set Z zero.
Then have a macro probe to the touch plate, and store it's location in machine coordinates relative to your spoilboard z zero.
Then, when you turn on the machine, you home it, and auto zero to the plate.
in your cam, you'd always set Z zero to the spoilboard, or bottom of your part.