That is a 26.5' trailer being pulled by an SUV......that is a lot of trailer for a 123" wheelbase. I don't think the EZ lifts have any kind of sway control system integrated with the WDH. IMHO, a 2nd friction sway control bar should be used. A better option might be to take the EZ lift back to the dealer for a refund, and buy WDH with integrated sway control such as the Equalizer (brand), Reese Straight Line Dual Cam, or Blue Ox.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263