How to install Backup Sensors on a 1994 Toyota Pickup?

[Student101]

Hi, i already have the sensors and all the needed equipment but i need to find a way of running the cables from inside the cabin all the way to the back of the pickup and to the bumper without the cables being exposed to water at any time. mostly i am looking to see if anyone knows how the cables are run for the tail lights so i can use the same route/channel. Ideas welcome!
Thanks