I can't see in the thread if the OP tried the trailer lights without any resistors. If so just plug it in without the resistors.I'm aware that the connector needs to sense a load in order to power the lights.
I was aware also that my 7L may have needed modification to connect a trailer with LED lights. The Treg even came with a load box.
However, I have not used either the load box or resistors with trailers equipment with LEDs.