In looking at the images, I would consider an C&V adjustable stem, such as made by 3ttt or Ambrosio, the extension will be horizontal, the adjustable fitting places the bars well clear and below the extension and from the looks of things you will be almost fully extended, making the visual pretty benign.

I don't think you will find an alloy pista stem long enough. Maybe a steel one like a Cinelli #2 or #3 drop, that could look Styling.