For the rear of the trailer I used plastic wiremold made by Legrand. It is made for inside use but I have seen instances of outdoor use where it is holding up just fine. Even in harsh northern climates. The trick here again, is to remove the existing tape and replace it with the automotive double sided molding tape. The old tape rolled off quite easily leaving no bad residue. I did clean it and the trailer siding with soap and water and rubbing alcohol. The tape sticks to both great and is very strong.
The channeling/conduit is split lengthwise and has a locking lip when snapped back together. I also caulked the sides after installing.
I used screws and more tape on the camera mount. Plus lots of caulking. The only part I might change down the road is the connection between the 18" connector wire from the camera and the connection it makes to the main cable. I didn't want to cut and shorten the wire and the connector is too large for the conduit I used. You can see in the picture I wrapped the wire around the bracket a few times then used loom and white tape on the short exposed wiring before it goes into the plastic.
The system works great and has numerous options controlled at the monitor for brightness, contrast, saturation, reverse image, volume etc. Yes it does have a built in microphone. The only time I turn it on is backing with someone guiding. It also has a remote.
Overall I'm very pleased with the system and would recommend it to others.