Yes a bike pump easily fills the bags as the max air pressure is only 35 psi. With the trailer on the truck and the WD hitch engaged there is still sag (bags show 7 psi) and pumping up the bags to 27 psi raises the rear and eliminates the sag.
What the Air Lift rep said makes no sense to me. If the bags put pressure on the coils to keep them from compressing to eliminate sag the truck would ride extremely rough as this would imply the coils would not be allowed to compress. It would also imply that once the suspension cycled (coils compressed) the bags would try to hold the coils in a compressed state which would result in sag and continued rough ride. It seems to me that the bags act in two ways; one to provide lift to eliminate sag and two to provide some degree of friction within the coils to stiffen the suspension. That's my 2 cents anyway.
