I would think that putting the ducts on the side and letting the air flow freely within the box puts less air pressure inside the duct and on the fan while heat goes faster away. It is also easier to utilize that heat space for other efficient things like drying stuff in your box.
Discussion
If you place cold wet stuff in that hot box, I think you could even let the wet drying stuff somehow make surface contact with the asic. Whenever water evaporates, it cools down, cooling the surface and stuff that it is sitting on like how your body gets cold if water is evaporating.
this could be a way to make the wet dishes dry AND at the sam time help cooling the hardware.