Take the rack off the back and put a 100 lbs or so as far forwrd in the trailer as possible and try. Your trailer is very similar to the KZ i had and the fresh water in mine was up front. Just the difference between it full and the holding tanks which were in the very back being empty made it tow better than when holding tanks were full and water empty. I still believe you dont have enough tongue weight. Keep adding weight up front. I usually towed without WDH as it was not needed and have never used a sway control device. I towed doubles with this trailer and had to move even more weight forward for this to work.
