I like the sound of it, but I can't picture it. It's kind of a good thing, because that will make the movie even more enjoyable.
I've read that scene in the books so many times and it's perfect. JKR does things for a reason. None of the characters get epic death scenes in the books, because that's not what it's about. Death is unexpected, depressing, shocking, sad, and disappointing. So, it's fitting that Snape dies in a shack.
However, I really like the idea of a glass boathouse.
Plus, JKR gave her approval. That's all that matters.