Another thing you can do is only fill it up halfway. With all those plants in there, he'll have lots of space to hide and move around, but he won't have to go very far to the top to get air. Many people do that with larger tanks. It's true that their natural habitat is shallow, but it's also long - the same thing that would happen if you only fill your tank halfway. You would have a nice amount of length, but it would be shallow.
Awesome gift by the way. I had to buy myself a tank for an early Christmas present for my new male that arrived 2 weeks ago via the post office - he's in a 3 gallon, my female is in a 5 gallon.