All I know is that a 50gal is 4' long and 18" wide, since that's what I kept my beardie in. But, since the most important thing for those guys, much like Blueys, is floor space, I think a 2' by 3' wouldn't be TOO bad.

EDIT: Just saw all the followup posts...you guys are fast As far as I know it's fine to house them together as long as each lizard has it's own retreat/territory.