The drag introduced by the bucket would help align your boat as a makeshift drogue. If you can find a way to rig it up so you can adjust the angle from port to starboard, you could very roughly steer.

Yes, the first line of the article. The rudder on the yacht fell off, so they were towed. In the middle of the pacific, the likelihood of a tow is low. In that case, you can fashion a rudder out of a line and a bucket.