persimmon, that office sounds awesome, except for the mold and respiratory issues. And as for a dedicated room in the house for plants, unfortunately I don't have a house that big yet. Soon tho!
As it stands right now, I have the tree indoors. With it being winter, the heat is on and so it dries out the house, which is why I bought a humidifier and keep it right near the tree. It sits close to a window that faces east, and it gets sun for a couple of hours during the morning, then whatever light filters in through the rest of the day.
I agree, Ivan Mann, that the greenhouse setup you described would be a lot for one tree. Once the warmer weather shows up, I'm going to be setting up an area in the backyard to give my tree (and others that I will be buying/growing) a proper setting for growth and health, so I'll look into fans and such then.
It seems that the tree needs more humidity than I am able to give it in the house. I mentioned setting up a humidity tray, but I don't have gravel; I do, however, have vermiculite and perlite, 2 materials known for their water retention. Could I use either of them instead of the gravel? I would think that, since they hold moisture, they would work better in this instance than the gravel...