I usually like to drive fast enough to essentially skip across the tops of the washboard rolls which seems to be between 30-35mph. In sand or on rocks reducing your tire pressure makes you have a larger tire tread contact patch and softer, more flexible and pliant face and sidewalls which help grab hold off, roll over or push through those sorts of obstacles. With properly deflated tires this can give you a relatively plush ride instead of the usual teeth-jarring, bone-rattling or wheel spinning.
For quick tire deflation duties I use a set of Coyote Automatic Tire Deflators.
They received good, consistent reviews on Amazon, were a step cheaper than the Stahn option and they are made in the US. I chose the model with the 3-50 psi adjustment range.
They’re quite small (36.7mm X 15.9mm/1.445″ X 0.625″) but feel nice and solid. Why? Well that’s because they are constructed of 100% solid brass. They come set from the factory for ~ 12 psi. Since I don’t have bead locker wheels I was apprehensive about airing down into the teen or even single digit psi range so I immediately swapped the factory installed silver springs (5-20 psi) for the included red springs which have a 5-50 psi range. After a couple of tries adjusting them, re-inflating the tires and seeing where they stop I’ve gotten them all to stop deflating at ~20 psi, warm, at sea level. It takes a couple tries but once you fine tune and set the psi where you want it you can assume it will just always work as you expect. They work incredibly easy. Twist on, pull ring, tires deflate to set pressure. Remove.
By the time you are done putting on the fourth one, the first one is usually done or close to it.
There is obviously some wiggle room when you factor in substantially higher elevations and/or wild temperature swings. I’ve used them from sea level to 7800′ or so and from 70 deg F to around 0 deg F and am seeing, at most, a 5 psi swing range. They still stop at the same psi as one another regardless of the environment though and predictable and consistent is good.