WDH's rely on the trucks rear end sag to work. If the truck is leveled first by airbags, adding a WDH will do nothing because you have no rear end sag to lever up. Using airbags only does not transfer weight forward so the weight is all carried by the rear axle (the amount lost from the front axle plus the trailer tongue weight). Therefore, you may exceed your rear axle capacity if you do not use a WDH. If your rear axle is not overloaded, you may not need a WDH at all. Therefore, my opinion is that if you have a heavy tongue weight, adjust the WDH with no air in the airbags and then add just enough air to start lifting the back of the truck but don't lift it. The airbags will stabilize the rear of the truck and you will get a better ride. Keep in mind that if you start lifting the rear of the truck to get it level, you will be increasing the load on the rear axle. If you are using a Reese dual cam or Equal-i-zer hitch, you will also be reducing the amount of friction available to the hitch which it needs by design to resist sway.
