You are correct that in nature no one props up the waterlilies so they are closer to the surface - in nature they just don't grow in water that's deeper than their preferred depth. That's why you'll see natural ponds with lilies near the shore but none where the water gets deeper.
I don't know of any evergreen bog type plants. All that I know die back if you're in a zone that freezes.
I'm a little concerned about your idea to glue your liner to your waterfall - that seems like it's asking for trouble.
I don't know of any evergreen bog type plants. All that I know die back if you're in a zone that freezes.
I'm a little concerned about your idea to glue your liner to your waterfall - that seems like it's asking for trouble.