That looks like a great enclosure, but yeah it could be a bit big. I prefer to go too small than too big with younger geckos, just to make sure they are able to find their food dishes and everything. Just make sure there are plenty of hiding spaces.

Go hit up wal-mart and find some sterilite or rubbermaid container. I've found numerous sizes that are PERFECT for intermediate gecko enclosures.

For your gecko right now you really don't need to provide 3 feet of height. I'd give it 10-12 inches or so of height and call it good.

Get something cheap and temporary.