You have some nice looking animals. I don't really know a whole lot about monitors yet though. they seem to be in good condition though.
I like the shape you chose for the hide thing in the bottom pic, but if you made more and made a retes stack you could get them up closer to the light and probably use a smaller bulb for heat. That or you could lower the heat lamp (I have a couple ideas for doing that in a cage like that...a way to make it adjustable and whatnot, email me if you're interested because it takes a while to explain exactly how to do it...it is a simple design though). If you do make more and stack them up, it would probably be a good idea to attach them together and anchor it somehow, just so it doesn't end up collapsing with your monitors on top or in it or something.