" I don't have room for anything bigger at the moment."
M M M M.....Maaaaybe he can be healthy there, if you let him out a lot. Whether he behaves or not. The thing is, letting him out dries his respiratory system, and he will more easily get Ear-Nose-Throat-and-Lung bacterial infections plus dehydration. The vet bills pile up high, because your iguana is sick and might die. He hasn't eaten in 12 days. He's very slugguish. Panic! We've been there. You have to spend the money. I have the room and can drum up the money, but I will never have another iguana. It's not fair to them.
I really love all the people who contribute here and ask questions here. I know you want to take good care of your ig. But your statement means that you don't have the physical resources necessary to keep an adult, healthy, long-lived iguana. They just get too danged big. The bare minimum width of an ig's cage is 2X it's snout-to-tail length. Not just anyone can care for them, for many reasons. We've barely scratched the surface here.