Maybe this will give you a little idea of pressures:
I have a 34', 17K pound F53 gasser with kitchen and gen on curb side. I have OE sway bars front and rear, firestone bags all 4 corners and a home-made trac-bar in rear. The installers labelled my bags at 60# drivers side, 70# front curb side and 95# rear curb (gens location). I think they simply placed the RV on a level surface and eye-balled it.
I'd like to soften the ride in rear with another pair of bags so they'd run at half current pressure. The right rear bag is almost max'ed and rock hard.