Iv'e done a LOT of these radar plug jobs. The guys on racing sailboats like to be able to quickly remove/install them. Lately Iv'e been using AMP products from Mouser.com Here's a couple pic's. I just douse them inside and out with corrosion block and their fine as long as they are below deck and don't get directly drenched in water. There's a grommet that goes on the strain-relief part.
