@SD: The height of the OSPi box is about 1.5 inch.
@skyynet: sorry to hear you had trouble getting WiFi to work inside the waterproof box. The power line adapter generally requires the two modules to be plugged into the same electric wire group directly (i.e. with no surge protectors, filters or transformers in between). So it usually works best if you plug them into wall socket directly and not anything that has surge protector inside.