The worst case of sway I ever witnessed was from a small, light single axle trailer. It was a rental from a military base. It was being towed by a half ton truck with the ball on the hitch and nothing else. I came up behind this guy going about 45 and he started to speed up. At about 50 I saw a small sway and it got much worse as he approached 55. He slowed down to 40 and it straightened out. I dropped back and followed until he turned off the road.
The truck was sitting level so he didn't "need" any WD but he did need something for the sway. Some posters have said you won't need any sway control with such a light trailer but I would question that. Properly loaded, proper percentage of tongue weight and you are good to go. What about a passing semi, a gust of wind or an emergency maneuver at high speed? Hmmmmm, I think it is better to get a properly matched hitch that combines both WD and built in sway control. There are many good ones to choose from.
