Pilots have been flying under bridges all over the world ever since mostly reliable planes came on the scene.
See barn stormers, wing walkers, etc.
Now if somebody did it with an SR-71 or the Spruce Goose, THAT would be exciting.
Under the seaplane exception to FAR 91.119 it might even be legal for the Spruce Goose.
Hi.
An SR71 would lose fuel at that altitude big time.
Be cool to see...
5.56mm