Quick drill that I have used with fairly good success ...
The idea is to try to establish the inside line to the ball, while forcing you to move your hips out of the way.
The essential elements are these ...
1) Put the ball further forward in your stance than you would normally do. (slightly inside forward heel for mid-iron shots)
2) Put a ball straight up from your forward toe, but CLOSER TO your body than the ball you intend to hit.
3) Put another ball in the center of your stance, but FURTHER FROM your body than the ball you intend to hit.
The idea is to hit the middle ball and try to push it out to the right.
Of course, you can't hit the other balls, and that is almost impossible to avoid if you swing outside-in (which I know isn't your problem, but still you will need to clear your hips to get a proper line to this ball).
You can vary distance and angle between the "gate-balls" to make the drill easier or harder.
The drill works just fine together with RHD and/or the pump drill.