Electrosys
Good to see somebody is thinking
Say the bucket was a flat wall. Then bucket would receive 1x unit of thrust & oppose this as 1x unit thrust reaction. Zero overall thrust to the boat.
However, the bucket has some curve. Despite much water spilling obliquely, It will throw some water forward maybe 25%. This would give an overall reaction from the bucket maybe around 1.25 thrust units.
Given the bucket is attached to the outboard itself, then, it would tend to tilt up. So case #2
Rex