What about this? Instead of the T's, I think just plumbed in series would be easier. It shouldn't lose much heat to the main heater.
I just recently replaced my T'Stat but reading back I saw the 195° T'Stat was recommended. Let's see how it works out with the 190° T'Stat.
I'm also now using this little guy as my heater (AC will now be on the left rear without a heater circuit: