Hi, I installed backup lights on my Passport a while back, pictures for it can be found at:
http://eaa1358.com/Passport/Backup_Lights/ these were replacements for the original Bargman 92 type without backup lights that came on my Passport. The wire for the backup lights was found in the junction box under the front of the trailer, it's the yellow wire and it was cutoff in that junction box so I had to splice into it and run a wire in wire loom back to the tail lights (I kept the color yellow), the pictures are high resolution so it will take some time to download.