These sound like they will be rather large dio's. Both sound like good ideas to me.. The only thing i would say about the first one is spacing. Aircraft tend not to be parked to close together. But i think its doable. 10 feet would be a reasonable distance in the real world, that scales to just over 2 inches if i have done it right.
As for the bridge, looking at a pic of it, it been cut in half and i can't see how a plane would do that. If it was flying on its side and clipped the wing on the bridge, the plane would probably spin off a long way but i doubt it would do that. You could still use the stone bridge, i take it your bridgeing the gap, but the plane would need to look like it had come parrel to the bridge not into it.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3