Your search for "rv tail light" revealed the following:
7-Way Trailer Plug Problems: What Do I Actually Need?
A 7-way trailer plug can carry your trailer lights, electric brakes, auxiliary power, reverse circuit, and ground through one connection. When something stops working, though, the first question is not “Which 7-way plug should I buy?” The better question is: what part of the 7-way system is actually causing the...
What Length 7-Way Trailer Cord Do I Need?
A 7-way trailer cord should be long enough to reach the tow vehicle through the trailer's normal turning range — but not so long that it drags, loops around the jack, or becomes its own failure point. The correct length depends on where the trailer wiring begins, where the plug...