Yes, just set an AF overscan and the last movement will be inward by this amount. In your example, the last movement will be inward by 100, so 40 for real backlash and 60 to move the focuser.
yes I’ve tried 20 as well either seem to work fine.
Starting out in focus or at least very close is very important. If you hit the donuts things go awry as they seem to get detected as multiple bits and thus seem smaller to the algorithm. I did try tweaking the detection settings to try and handle this but once I got it working I decided to leave things rather than try and perfect things which usually makes things worse for me.
I also use the annulus settings to exclude edge stars as they are pretty bad on my setup for some reason I’ve yet to resolve though I do have some ideas for more spending