SuperInk5 Pack Dustproof Electrical Junction Box Connector 5 Pole Waterproof Enclosure Case fit 20mm Cable Gland for Outdoor Use (86x74x62mm) IP66 Rated

This meets the criteria for being waterproof--my only concern is the knock-outs are not as easy to pop-off as they are on metal junction boxes. I preferred to drill them out (drill press works best, to prevent cracking the screw holes on the back), but one could use a cordless drill.