I've done it! My family took a canal boat trip for a week when I was in high school, and we went across that aqueduct as part of the trip. It was a pretty spectacular view. A little unnerving, because at least when we did it one side of the aqueduct had about a six-inch lip above the edge of the water and no other railing, but gorgeous.
I nearly jumped out of my seat when I realized where they were going.