12 volt power is a challenge when it comes to plugs and sockets. The standard cigarette lighter plug is a pretty flimsy connector, yet it shows up all over the place. The European cigarette lighter plug and socket are much heavier duty, but they are an interior design, and not intended for wet locations. They show up fairly often in ambulance modules, though.
I found another option, and it's one that I have decided to use for any plug-connected 12 volt equipment in my ambulance. The connector is available in 2,3 & 4 pin configurations, it's rated at 20 amps, and it's designed for weather exposure. It's a standard for plug-connected solar equipment as well.
The plug has a cable connector that can handle up to about a 7/16" OD cable as well, plus it has a rubber cable grip incorporated in its design. The receptacle has a rubber cap for the connector's sockets as well.
It's available from Amazon:
https://www.amazon.com/gp/product/B072JJHPZ5/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1