Most household thermostats cannot EASILY be made to work. (they can but at great effort and cost it simply is not worth doing)

You may find a johnson or ranco at an appliance repair place but on line a good option there.

A note on the humidifier it isn't very difficult to get one with an adjustable out put and set it every few days the controllers are expensive. I use this myself and change it twice a week when I add water to it.