It's hard to bring up glass, as so many people will ridicule you for it.
In my experience, airflow can be chieved with good circulation - like a
fan in the room. Also, I've come to believe reflections are not the major
concern with chameleons - transparency is.
If the chameleons can get to the glass, they'll try to get through it, as
they dont' recognize it. If they have a nice cage, and don't have any
reason to roam, you don't have any problem.
The absolute best chameleon cages I've seen were glass or acrylic
fronted, with screen sides. The glass was not near any branches, so the
chameleons couldn't reach it - and they would't spend time stressing out
trying to climb through it.(and it stayed clean - no paw prints!). There
was plenty of airflow with screen sides.
The only time a reflection seems to cause a problem is if the light in the
room is very dark - it makes it more reflective.
As long as you have good circulation and ventilation, and the chameleon
isn't able to paw at the glass - a glass door (or back)is fine. An all glass
enclosure has so many drawbacks, it's almost never worth it, in my
opinion.
Funny story - a guy came into the pet store I used to work at in 96. He was gettign some CB jacksonii to put in his new cage. He built it himself , and put $300 into it. It was 5'x4'x2'deep, with waterfalls, live plants, trees, and 3D background, with plants mounted in it. he showed me a pic - very nice.
I asked "Did you use a large mirror for the back of the cage?"
He did.
The background had several parts that were 3D outcroppings, for plants and the waterfall - like what you'd see in a nice dart frog setup. But the rest was all mirror! My god this guy was pissed. He didn't want to hear it that a mirrored background wasn't the best thing for a male Jacksonii.