I hope you're not planning on moving it anytime soon and making it in the permanent location...That will weigh a ton with 3/4" melamine and two stories...

Kudos for the idea, but I'd suggest just going for a good 8x4x2 or 3 cage and set-up him up nicely...You can even make it a single story Taj Mahal...Then you can put the rest of the money to feeding that big boy...