I have an update.

After the rear steel bumper installation, the rear suspension settled a little bit. Then, I took the Rodeo to the Pismo Beach sands, and that's where the real beatings happened. In soft dry sand, in large hills, you cannot drive slowly and carefully; you must maintain really high speed not to get stuck going uphill. The surfice is fairly uneven, it's like a giant washboard with uneventies of about 1/3 of car length size. Going 30 MPH on such a washboard makes you feel like in ... well, there is nothing to compare with. So, as I mentioned, the suspension got good deal of real beatings. This made it to settle even more. The initial setup was very tightly calculated, so no wander that after that my truck began to bottom out my really long shocks, on compression cycle.
I could fix the problem by dialing the shocks firmer, but this would not be a good solution.

I ordered and installed new 2" coil spacers. Now, it bottoms out no more. My measurements show that now I have about equal uptravel and downtravel.

Everything else is perfect.

As for the sands, I saw some really well-prepared full-size pre-runners trucks going like 60-80 MPH on sands, and believe me it was impressive ! Their suspension was able to absorb the giant bumps so easily and so smoothly I could not imagine that it was real.