I'm not convinced that all RT trailer wiring is alike. I have a 2011 RT-S SE and tried to follow the pigtail schematic that Steve shows in his Mods thread, but it didn't match with the readouts I was getting from my RT's tongue harness. I purchased the BRP harness 710002029 and have an Aluma MCT trailer with a 5 pin flat connector. When I tested each wire from the tongue harness (connected to the RT), I discovered that the Red and Orange wires controlled both turn signal and brake lights (Red=Rt Turn/Rt Brake; Orange=Lt Turn/Lt Brake) and the Blue, Green, and Yellow wires had no power when I tested for running, turn, brake, backup, and 4-way flasher. So I basically ended up with a 4 wire tongue harness, plus ground of course. I would strongly recommend testing your leads prior to soldering or connecting to your trailer - this is truly the only way you'll know which leads go to which wires on the trailer.
I also need to mention that because the turn signals and brakes were coming off of the same lines, I had to replace my trailer's brake light with a combination LED light (running, brake, turn signal) otherwise the entire brake light flashed when I had the left or right turn signal on. I probably didn't have to replace the brake light because I could have simply ran the turn signals off of the lower lights, but I wanted to have more than a running light towards the top of the trailer.
View attachment 43323