I"m with you! Snakes are decorative pets, they need good "frames".
Your idea to turn it on it's side and make the crack the back sounds good. Hope it works good for you.
Does that make the top the front? If so you might want to make a plexi-glass lid like this guy.... YouTube - Plexiglass lid tutiorial
He's my fave do it your self tank retrofitter, he does some great polystyrene type background tutorials too.