What cutter? In the settings you can edit the placement and margins (for summa at least).
Found it! In case anyone else tries to find this:
In onyx thrive:
Go to File/Manage Cutters (click yes when warned about configuring the server - make sure you're not in the middle of printing any jobs)
Select your cutter (click on the line, not check mark), click Configure
This will show your mark settings
Mine are both pretty different (attached). Edited to add: Oh right, you can't actually reduce them much more than that. So this wasn't much help at all. Why would they lock the minimum offset values? I get if it's too close the camera might confuse the print but it sure wastes a lot of material (and time).
I also wonder if there is any difference between using Summa or Onyx barcodes for the F series? (we don't have camera/barcode feature on our older S140T)