Looks great, Dinonykos.
I just happened to be working on the same thing yesterday.
I have an underground pond and stream that I had done as backdrops, but have started to redo as walls, using the hyper walls.
I've said it before, anything you can do with walls, you can do with backgrounds and vice versa. The caveat is that for some things may be more work than the other while the other may look a little nicer.