16 rear and 20 front for me. I tried 20 rear also but there was nowhere the amount of bulge in the tire. Also - the type of tire you use makes a huge difference in the sand. An aggressive mud terrain with lots of sidewall traction helps a lot. All terrains don't seem to move as easily. Sugar sand is very loose - you need as wide a contact patch on the tire and they should sink in a little allowing the sidewalls to help bite.

 

8-10 psi here

 

Well I'll throw out my setting but they are pretty much what 4crawler said.

My tires are 295/75/16(34" 12.50"), I like to run around 5 for a nice big footprint and to help with floating. If I stay around 10-12 i find the truck works too hard, even with the charger. At hight pressures it always feels like it wants to dig, at low I can get good wheel spin for hill climbing and not sink. I have decided it is time to look for paddles so I can do some crazy hillshooting/ keep up with the rails.