If using Soft Power, you shouldn't need proof of income(that I know of) as someone said earlier you can sign up for a cooking class or Muay Thai course. Try....
For family reasons I need to travel often to and from the states. They said I could do one week at a time for as long as I needed. In other words, no need to do all the weeks right in a row. Plus.... I don't think you can fail. It's cooking, you eat what you cook. Lol