I've now hooked up my hidden air horns and also finally installed my power outlet. Thanks to Curley Wolf for the install location and source.
I'm looking for an insulator for the back of the power outlet (cigarette type adapter). I thought something like a plastic or rubber boot, similar to that used for a wiring harness. This will be used to protect the rear of the power outlet from the weather, baths, etc.
Any suggestions will be appreciated?

Checked all the local auto parts and hardware supply types.
Here's a shot of the power outlet install/location.
