Becca, I think those fans will do great for you! Yeah, it's a lot of fans to get but it's better to be safe. I was just thinking of getting another one just in case! You never know when an emergency will arise.
In my Exo Terra I just have the fan sitting on the bottom grating (I have prima agra at the very bottom and egg crate on pvc above it). I have never fully decided how I was going to mount it somewhere so I just plopped it there.
But it seems to work fine but I'm sure it blows some of the humidity out. Maybe someday I will figure out something better.