I actually have a very similar setup except it's my storm cellar that is inside our basement, I know someone said something about humidity problems, To be honest I am currently having humidity problems but that is only because the cement walls are leaking water from the soil surrounding it (Our water levels were extremely high this year) If you can keep that room dry, you could easily get the humidity as low as 40% or so without a problem.. A really good solution if you could get your hands on one would be a window unit, the way they work is pretty much perfect for sucking humidity out of the room and bringing dry air in..
If you don't have water leaks then your solid and just a few fans would do the job, my cellar is about 10 feet underground and the walls stay a constant 73(at the floor) and about 78 on the ceiling of the cellar.. Fans would easily compensate for controlling the environment perfectly..