I know that the size of this facility is probably in no way a credible way to accurately guess the size of the 004, but if that plane on the bottom were suppose to represent a J-15 sized plane, even being a bit conservative. This flight deck is absolutely humongous, ~400m long. The Catapults would also measure out to be around ~130m. Again Just something I find interesting, don't take it too seriously.
It's worth measuring it out fully.
They didn't construct this aircraft carrier mockup unless they were actually testing and verifying the layout.