Yeah, 2 foot deep is enough. Make it taller, they like a bit of a climb. Normally over big rocks and stuff, but a few like to hang out on branches.
I make all my enclosures in 6 foot long, 7 foot tall banks. I always have a 100mm kicker at the bottom, too. So if I were you, I'd make the enclosures 6 feet wide, 3 feet tall. Make it so it splits in the middle for easy manouvering.
Were you once at Bunnings looking for a spot globe, and a slighlty overweight (fat) bloke with a beard overheard your conversation?