Alright if you check your temps and snakes everyday there is more than enough air circulation when the door opens and closes. If only once a day its still good enough. So that should take care of the fresh air and air circulation in and out of the room.
I would also have the fan turned reverse so that it pulls air up rather than force air down. Snakes don't like drafts so much and the inversion will help with airflow.
If you are concerned with humidity go buy a little warm air humidifier. It will have to be refilled everyday but you will be in there anyway right?
What do you do about heat in the winter? How big is the room? Is the garage heated or cooled?
-----
Jeremy
"I am become death, the destroyer of worlds" July 16, 1945 Robert Oppenheimer
1.1 Double Het "Sharp" Snow RTB's
1.1 Hypomelenistic RTB's
0.2 Pastel Hypo RTB's
2.0 Double Het Stripe Albino RTB's
0.1 Suriname RTB
0.1 Anerthrystic RTB
0.0.11 Red Bearded Dragons
1.1 Rhinoceros Iguana's
1.0 Green Iguana
1.0 Ball Python
1.1 Cream Golden Retrieviers
1.0 Pomeriaian
0.2 Catus Terribilis
0.1 Spouse
0.0.1 Youth -coming soon-