I had an enclosed car trailer that sat high so that the car's doors would clear the trailers fender wells inside. The trailer was very unstable behind my Suburban with standard WDH and one friction type sway bar. The taller ride height certainly doesn't help matters. I ended up adding a second away bar and it fixed the sway and actually pulled really well. Your truck shouldn't have any issue at all pulling that trailer. I would add a second sway bar and snug them both down really tight. Also make sure your spring bars are sized appropriately for the tongue weight of your trailer and that they are adjusted properly. The tongue of the trailer should be slightly lower than the rear of the trailer.
