It works just as expected, I'm happy with the construction and performance. I'm anxious to see how it works after a few more outings.
Yea, slips very well into the original bag, see below. It's a tight fit. Depending on your cozy material thickness, this might not work for you. The window/shade material I used is really glorified aluminum foil and not very thick.
I plan to make another version using old beer-can cozies....those are also available cheap at the $$ store. I like the idea to use them as pot-holders too.