Gregg's Duck Box Placement Suggestion...

Wood ducks prefer areas of seclusion. Mature trees and or vegetation are much preferred over open areas. Nest boxes can be installed on land or in water. On land, a shoreline installation is fine, but not necessary. Wood ducks have been known to use tree cavities and nest boxes up to a mile away from water. Land-based boxes can be monitored on a walk-up basis, do not require boats or waders, and eliminate worries about varying water levels and bending of poles from ice-out conditions in the north.

When installing a nest box, the compass directions the box faces is probably the least important consideration and should not be the determining factor. 
Box usage is more likely to be influenced by a smart installation that accommodates the hens' accessibility and flight path to the box. However,
we sometimes attempt to do the hen a favor by slightly altering the direction of the nest box opening away from the direction where storm patterns usually develop (locally, northwest and west).