So far, everything you have stated should work. My GH's are what I use to over-winter my tropical plants, from November through (at least) February. The orchid "teens" and mature ones go outside for the other months. What makes a GH so useful, is not only because you protect the tender plants from cold but also because it maintains high humidity (even in the desert climates). Tropical plants thrive in humid conditions. The downside of humidity, as all of us in the south knows, is mold and mildew. That's where the fans play an important part.
