There's no reason you can't use air ride with WD. I think that's a myth based on the fact that light-truck air suspensions had you turn-off auto-levelling until the WD bars were installed. That said... is your receiver rated for WD? If if doesn't have a WD rating, and is only a 4-bolt style receiver, it probably is not designed fro those forces.
Probably just need to scale it to know if you need WD. If you're over the rear axle weight with the trailer, WD might bring you back under. Just stop at any closed ODOT scale. I think it's unlikely your front axle would unload too much. The one by the Corvallis landfill on 99w has a nice wide driveway, in case you wan to do a 4 corner weight, and it's almost never actually open.
