I have never tried to extrend the season on the back end. By this time of year I am about done, and so is the garden. Its time to rest. On the front end I have tried to push the season with a hot bed. I have to say I had very limited success. My nieghbor has a greenhouse and put tomatos in pots in there one year. They had been dying back with blight before he put them in. They regrew and produced until Dec when he had to remove the extention cord that ran out his bedroom window because it was getting cold in there,
He also has hoops that he built into his raised beds so he can cover them in plastic. I would have to say that he uses them more in the spring than fall, but they would work either way. I have never tried Kale, but have heard the same thing as you, very cold hardy and produces well into the fall or winter. This year the Farmers Almanac is calling for a very cold winter. If it worked this year it will work any year, why not give it a try. Whats the worst thing that can happen? It doesn't work and the plants die, Oh Well,
you will get one of those Learning Experiances that we all talk about.
Never doubt that a small group of dedicated people can change the world, indeed it is the only thing that ever has.