Wow, didn't think tires in our size range had a max pressure that high (70). Anything near that high is going to give you a very hard tire and I believe some very hard jolts in ride. My 295/60-18s max is 44.

Driving at max psi will maximize your MPG. Over that, tires can wear unevenly down the center, way under that, you'll see more wear on the outer sides.

Ranchos:
I keep my Ranchos at 4/4, for both highway and general. I do get a little bit of "float" or "bounce" with the Ranchos at 4, but only over my rocky road. Lower than that was too bouncy for me.
For off-road Rancho suggests 6/4. This yr in Moab I forgot to up the fronts , and I felt a lot of bouncing on the trails.

PSI:
My tires are at 41 psi. I found 44-45 psi was just too hard of a ride.

I "think" you might want to first find a Rancho setting that you like, then play with psi.

And lastly, have you considered cutting your rear bump stops in half? That really was the 3rd leg of this stool and improved the ride.