Alvinc, you are comparing apples and oranges. A dinghy with four wheels on the ground is stable to begin with and will track when properly aligned and the tow bar installed and centered. A travel trailer is "balanced" on one or two (sometimes three) axles. The axles are placed behind the center of the trailer which makes the trailer heavier on the tongue. If the tongue is too light in weight (less than 10%), the trailer will have a tendency to wiggle or sway with its pivot point at the trailer ball. Move enough weight forward and have a tongeu weight that is higher, this wiggling or tail wagging is minimal to non-existent. Too much weight to far back will have the tail wagging the dog.
A friction type sway control will dampen the side to side wiggle or sway. Better is a Dual cam that uses a force and a cam action to try and keep the trailer straight. Last is a hitch like the Hensley Arrow which uses a link arrangement and creates a projected pivot point that is closer to the rear axle of the tow vehicle. This keeps the effort that is wagging the dog closer to the rear axle as in a 5th wheel hitch and has much less effect on the tow vehicle.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot