Well done, but note there is a maximum temperature difference you can maintain across these devices. If you push it greater than this maximum the effect breaks down and it all heats up. So see the data sheet for how far you can push it.
I wouldn't bother controlling the fans, just keep them on all the time. The commercial one I had for keeping my son's injection medication below 8C when camping would flatten a car battery in about two hours if the engin was not on.