I did a TTD in my real dress, it was a water one in freshwater, up at Buderim rainforest park. I had it dry-cleaned immediately after, and it came up immaculate, no damage. There's some more pics in my hall of fame thread.
I toyed with the idea of having a replica made, but then decided against it because for me, it felt like the TTD wouldn't really have the same significance then, as it wouldn't have been my actual dress. And if that was the case, I didn't really see the point in romping around in the water in a dress that I had purpose-made just for that occasion, IYKWIM.