"Check your arithmetic;
With the 5th wheel set over the axle, that 6000 lbs would not change the front axle weight, because air ride keeps ride height the same.
Question; When you unhook, do you crank (or power) the nose up until most/all weight is off truck, or do you crank 'til legs solid on ground, then dump air?"
Not much to check I simply add right about 6k to the truck, of that at least 150# is added to the front axle. My hitch is set either 2 or 4" front of centerline of the rear axle.
I can't dump air. I go into setting and select tire jack mode so the truck does not try to move while raising RV. Once I see the hitch head start to raise slightly from the hitch base I stop and unlock handle non open it and pull away. The truck goes off tire jack mode once I start it again.