This is exactly what happened to me this spring and this is exactly the same way I fixed this problem. Flexible pipe through the passage and silicon around the edges, water cannot escape sideways into god knows where now. Should be fine, I haven`t had any problems since then. But I know the misery of trying to dry the floor lining and carpet, with me water had spread far behind front seat, the level reaching an inch under the mats. Pretty horrible it was. Looks like a common thing on the 600s though. I think everyone who loves his 600 should do this pipe trick, it really pays.