I don't know if I have "THE" right answer but I've also thought I've got a leak in mine.
I pulled off the entire light and can't see any water or dirt "trail" getting between the light housing and rv siding, so I called it good.
Then I took off the lens and saw where water was making its way into the light lens and then out again. But the lens screw is rusty, so some water is making its way where is not supposed to.
I put a little putty tape on where lens makes contact with actual light housing and will check in spring.
Hoping somebody replies that has really good idea.
I have the old style Barge. I wonder if the newer LED type is a sealed unit? If so that would solve my problem as far as leaking into lens.
2003 Majestic 23P... Northwest travel machine
2013 Arctic Fox 25W... Wife "doll house" for longer snowbird trips
2001 "The Mighty Dodge"... tow vehicle for "doll house"