Well I have to say that, personally, I would prefer an enclosure.
However, if things are working you may be okay for awhile.
I do think more water needs to be introduced...via some sort of drip system.
something that is rarely mentioned is the feeling of security that a screen wall provides for a chameleon. They seem to be much more comfortable with that barrier between them and the rest of the world they can see.
Tyler has some good size enclosures for really good prices in the misc. classifieds right now.
Again, things seem to be working out okay, but I think you should make this a priority in the not too distant future.
-Brad