I was wrong. Most OEM's are stating a procedure for their auto-level systems as noted by Ron that levels the truck/SUV prior to connecting the WDH.
I am not convinced that is the best method. But I don't own, and probably will never own, a truck or SUV with self/auto leveling systems (its a personal preference) so I cannot experiment myself.
But I have towed significant miles with 2 SUV's with aftermarket poly bags installed, and I follow exactly what eTrailer spelled out. WDH first, and air up for added spring rate, with very little if any height added.