I did it without cutting or splicing anything.
I ran a pigtail (bundle of wires) from the connector I installed at the hitch along side the wire bundle already tied under the fender. ran it around the front edge of the fender then up into the battery box (had to make a small hole in the bottom of the battery box. Then I simply piggy backed the wires to their corresponding connection in the main harness....no cutting.......just ran each wire through the hole in the male portion fem back to front then bent the wires over the end so they were now facing back and then re plugged it in.
I could get away with this direct hookup (without a relay) because all my trailer lights are LED ... very low amp draw
I did practically the same thing as Chris.
Only difference was I run a loom under the saddle bag up to the right side cover.
Matched the wires up stuck the trailer wire in the hole of the matching male plug and soldered it.. Been on there for almost 12 years now. Opps, forgot we took it off yesterday since I no longer have a trailer.