You might want to rethink doing that, read Neon's post above yours as it sounds like doing this will put more heat onto the panel and actually accelerate the issue. Personally I would try and cover the car though that means having to keep it clean so as not to have dirt scratch it.
With Jeeps you can get partial covers that only cover the top to the bottom of the windows but have never seen something like this for a smart, might actually be a handy thing.