Glad you found a setting that works for you. Do I understand correctly that your primary concern is the line weight, not so much line smoothness? Was your issue that the lines appeared wider when using a Multisample anti-aliasing setting larger than 0x?
For background, in theory the Multisample anti-aliasing setting should not impact line weight. If you see different line widths for different anti-aliasing settings that may point to a bug in SketchUp’s rendering code.
Also, I notice in the screenshot you posted that “Use fast feedback” is turned off. Is that needed to achieve the look you want?