The etched board looks like it was from laser artwork. The undercut is no greater than the width of the jaggies. Why would the undercut be any greater with a 5 mil track?
Bottom line, you shouldn't have to try 6/6 or 5/5 rules in order to determine whether it can be done. You should be able to determine that by inspecting your 10/10 rules results. If the printer is the limitation then the artwork is going to tell you that before having to go any further.