I did some water testing on the black box.
in both the horizontal and vertical positions it did allow water into the box.

In the horzontal, IE, the screws are visible looking straight down at the box, there was enough water pooled at the bottom, that I would be concerned. Very short test. Used a veg sprayer in the sink to hit it for about 30 seconds. About like if you hit it with a power washer washing your car.

Mounted vertical, with the long axis being hit by water from above, it was much better, leads me to believe the screw holes are the weak link.
A few drops of water pooled at the bottom.

I will test out the white box in a few days, but if you chose the black one, mount it inside would be my sugguestion.
OR, tape up the edges and screw holes.