I'm getting a front to back rocking motion towing at highway speeds. Lower speeds are ok. Trailer is an 18' with a single axle. I've gotten several opinions and all seem to think that I need more tongue weight. The winch unit is adjustable, but my question is in what increments do I adjust. I've been told everything from an inch to 4 inches at a time. If anyone has had to tinker with their trailer this way I would sure appreciate the input. Thanks in advance for any responses.