You're really thinking outside the box here
Having said that, I had a few thoughts after reading your post. Our coils are kept cool because the juice is in contact with them and transfers the heat so well. This is why you can put a waxed paper container with water in it on a fire and the paper won't burn while the water heats up. Put a coil under glass and you would have to either form the glass around the coil or use a heat transfer medium to make proper contact between the coil and the glass. Also, Pyrex can take a lot of heat, but I doubt it would hold up long to vaping heat cycles. 200 hits a day over a month is 6,000 very short, quick cycles. There is also the issue of heat up time so thin is better as you said, but that means more stress on the glass. There are other materials you could use too which would stand up better. I see lots of experimenting in your future!
I agree airflow can be achieved without too many problems. You could try making the heating element/glass cover like a dished doughnut and have the air flow through the center.
Well, I don't want to put a damper on your idea! Just trying to help a bit by sharing my thoughts. More ideas are always a good thing
Now go for it and best of luck with it!