Check the setup of your WDH with the air leveling suspension OFF. When ON it disguises poor weight distribution by self leveling but that doesn't move any weight off the rear suspension. Switch it back on when done to take out the last 1/4 of level. It's not about "level towing." It's about weight distribution.

The key with a WDH is to measure the suspension heights with the truck just sitting there first. Ground to top of outside wheel well is a good measurement. Then add the trailer and adjust the WDH settings. The front suspension MUST compress or you're not moving any weight off the rear. Ideally both should compress the same amount and leave your trim at the same point albeit with some suspension compression all around.

-- Chuck