Hey Bill,
If you have the tool setter in a fixed position, the most simplest way would be to always set the workpiece zero on the bottom of your virtual 3D model. If you do this, you would just be required to record the tool setter’s height of triggering point just like with the XYZ touch plate so that it is substracted automatically on every use. This is done in the line with the G92 command. I have a variation in my Aiph5u’s tool change routine for workpiece zero on machine bed at the end of the posting there (you just need to comment a line out for probing on machine bed).