Track overhang relative to tool bay

I am moving my farmbot to a new planter when I disassembled it I did not record the length measurement of the vertical mounting plane of the tool bay horizontally to the end of the track. What is the ideal measurement for this so that the UTM can pick up a tool without the gantry hitting the end stop. (Running a v1.0+ farmbot Genesis)

Can someone provide this measurement? Or provide a link to a documentation page or drawing?