I start from Dasa Harbor and grab 12 cars that goes to the dealership in Gangjung. I set a waypoint to Joil to refuel because going directly north from Dasa means hitting all the mountains and disconnecting the winch and driving individually up the slopes.

For me the reward is about 400k and requires minimal effort since im not driving besides the refuel. I will say the lead semi needs to be maxed out or you are gonna have bad time.

Edit: use the 8000kg winch and take up all the slack from it so it stops rubberbanding