It makes a big different doesn't it! Loads more space. I like the idea of the cage mounted litter tray making another platform. You need to be a bit careful with ladders with rungs though. Filled in ones tend to mean a few less accidents. You could easily fill in a runged ladder by sticking a hard piece of cardboard or thin piece of wood to the back though
I also worry a bit about chains with rings. Hammies can get their toes caught in them and end up hanging by a leg. It could be an idea to get hold of some sisal string or paper string to use instead of the chains, if you can get some.