My suggestion would be to look at the Marine Store's or any Marine Parts house.
I would do the Cigarette style so you can unhook the Sat and leave the Plug on the side of the camper.
12V Waterproof 16A Panel Mounted Din Socket + Cap
the 1st pic looks like it would be a nice fit since it has a screwed on cover instead of a pressed fit
the 2nd pic is made by Marinco and its called a Seallink - it has a rubber cover which over time becomes loose and eventually breaks off so I do not recommend that for your application