Just use a tail light converter with the 4 pins plug that go to the trailer on one side and 5 wires on the other side like this one:
Those are wiring harness plug that go to the brake light
White = Ground
On the driver side:
blue/green go with yellow = Left turn
green/black go with red = Stop
purple/green go with brown = taillight
On the passenger side:
blue/brown go with green = Right turn
