[cypher]

I would take the shelf out too if you can then jus fill the base completely with substrate & put the house where the shelf is now, the coconut is more of hideout or place to explore, it's not suitable as a house, you could put a little substrate in there or some shredded up plain white toilet tissue & then hide some of his food or treats in there for him to find.
If you can find a cardboard box for a house then you could use the top as an extra shelf area for now, if need be use a wooden bendy bridge for access.