Ken, you absolutely should do both D03 and D04 in the same year. You are more than well-positioned and ready to do both levels at the same time. I think you will really enjoy the musical experience and challenge of aiming to perfect twice as many pieces.
I agree that listening to and watching other players, including your playing, is helpful and I can learn a lot from doing just that. Moreover, Colin mentioned in another post, that next year, mp3 submissions will no longer be acceptable for either the exam submissions or the monthly lesson submissions. That will ensure that I will not miss out seeing the actual playing technique of some of the good players, like your colleague Patrick and the student tutor Francoise, both on the French board, who preferred mp3 recordings for the lessons.