You could totally use it for upside down, you just leave 2 inches at the top for an air pocket! I, however am very much in favour of the moss wall carpet. Put some corkscrew vals & maybe some java ferns in there as well and you could have a very nice looking little aquascene.
I am honestly so grateful for your painting. I almost have tears in my eyes from laughing. Firstly at my illiterate spelling and secondly because I was just thinking how helpful everyone is with ideas. I thought it would just be too much to ask for some kind of diagram on how this should all look but you...MistersMom have done wonderfully haha thank you.