Have the fan directly facing the falling water if you can, otherwise you may loose some of the cooling effect there (where it'll be largest).
If your worried about moisture in the air, maybe seal the box and use a 90° adapter to pull water in from the top of the box to the fan? Tho spose then you still need a air "outlet" somewhere which would still be pushing damp air back into the room.
<edit> Lower CFM 120mm might be better as you'll be cooling a larger area of water at any one time. + it'll be quieter and probs push out more air than a 60mm </edit>
<another edit> How about using a tuppaware/microwave plastic bowl? Asda or similar sell decent sized ones for under a quid. Stick the bottle to 1 side to contain the water. Should be nice and watertight + they come with lids which might help minimise splashback and damp air escaping? </another edit>
<ooo another edit> Last edit would look just like your last pic... </ooo another edit>