This seems to be causing the double thickness issue that I was seeing.
The camZBottom value seems to always be added to the thickness of the part being cut.
I worked around it because generally I actually do want to cut slightly deeper than the actual wood thickness just to make sure that I cut all the way through so it’s not an issue, but gcode generation does fail if someone wants to cut to exactly the thickness of the wood.
I recognize it’s pretty hacky, but you can slice the bottom layer specifically by setting a really high down value in the outline op. heres’ how I did it: