Yep, It may be smart to have sufficient copper to wire each fan individually. Getting the wire through the drain hole is a bit of pain in the arse so only do it once.
I spent all of 30 seconds making this drawing but it works if you are powering the fan and relay with the same voltage. We've found placing a fan to blow air across the cooling plate helps reduce condensation. Industrial strength Velcro adheres to the back of the NewAir better then standard Velcro. Do not place the fans near or over the drain channels in the back wall of the unit. I use computer slot fans because they save shelf space but any low voltage fan will work fine. Check placement of the fans before securely mounting. They may interfere with the shelves. I run the fans for 10 minutes every two hours but the timer is very flexible.