Given that you are going to cook a special soup, and you must make both salty-taste and light-taste people feel satisfied with the taste of your soup. Is it possible? Could you come up with a method to solve this issue? The possibility of moderate taste has been eliminated.
Make the unsalted version, serve as many as you need, then add salt to the remainder. Or just serve the unsalted one and put some salt on the table(s).
Roman is right about that. I've seen a lot of restaurants serving light one in big ware and you can get people a bowl and add salt as they wish.