There is more lighting present than may be seen in the pictures. Although your right and there is no metal halide light available, I don't find it necessary as I've raised many lizards of similar husbandry requirments under these same conditions.

As far as a bigger cage, check this is their home when they get big enough. 10 feet long, 6 feet wide, 6.5 feet tall. Think it'll do?
Paul