The first thing I think of when I hear an AC/Ground mix is Scale.
It's difficult to get equal scale AC and figures and even harder to get equal scale AC and AFVs. I thnk 1/72 is the best bet.
I would recommend taking some time to paruse the gallery and scout out all the different layouts of dioramas.
One thing I have noticed with AC crash dios is the 'skid' path or AC damage is usually commented on. The path isn't natual, or long or deep enough. The respective damage to the plane is commented on too. Wings torn all the way off, props bent, canopy position, fire, etc?
I would read this feature by Eagle
Diorama Feature Then sit back and plan. That will generate more specific questions.