XF 2.2 Is there a way to add a CSS class to the username if a custom user field is set?

For example a ".username--style3" class is added to the administrator group if custom css is present. Similarly, I'd like to add a class to the ".username--style2" class if a custom user field is set, or is there another way? I tried adding a custom user field and setting it to any option other than the default but I don't see any extra classes produced on the front end username when having done so. Do you have a solution?

To clarify, I'd like to have either class="customUserFieldSet" or something like data-customUserField="On" to the "username--style2" span just like for example how "username--moderator" & "username--admin" are added to the "username--style3" class, this way I can style all usernames with custom CSS which have that particular custom field set. Optionally, is there is a primary username template which xenforo calls that I could edit?