[JRTJH]

Think about it this way: When hitching the trailer, we use the trailer tongue jack to lift the hitch, reducing the weight on the bars so we can lift them into position. In other words, we "lift the tongue to reduce weight on the bars"...

When you hitch the trailer, set the bars for proper weight distribution and then "inflate the air bags".... You essentially "lift the hitch and unload all/part of the WD forces" you had previously applied to the front of the tow vehicle and to the trailer axles.

Any time you change the hitch height you need to then reassess the WD forces being applied by the WD bars.

So, if you hitch the truck, set up the hitch, then inflate air bags, you (at a minimum) need to reassess the WD system to be sure you haven't changed the hitch WD function.