We sometimes get requests to run all Axis vs all Allied planesets. Some would resist this because they don't want to see Corsairs battling 109's in AvA, but there is a way to get all countries plane sets on the same terrain, with minimal mixing. It would require a World at War map and different theaters would be represented in different areas.
It would encompass multiple textures like in the current thread about that here and would be ridiculously out of scale with continents fudged big time, but still might be fun to have the whole war going on in one arena.
This is a crappy pic I whipped up, but has anyone ever tried to make something like this?