If I’m only running sand dunes and not much high speed on hard packed and not planning to do big jumps I run 14 pis front and 12 to 14 rear. A few times I’ve got into some really soft powder like sand and took the front down to 12 psi. This is on stock none beadlock wheels and stock tires. As far as popouts if you keep it smooth you shouldn’t have issues. If you are running a stiffer sidewall tire than stock you probably need to run a few psi higher.
If you do get a popout you can generally pop them back on if you have a good compressor or and jack. Jack it up to get all the weight off, clean the sand from the bead area, pull the tire toward the bead area with the compressor going and usually it will start to hold air and reseat.
for modes I generally put it in sport mode, turn dial to 4x4 and then disable both traction and stability control. The mud and sand and also baja works too but Be sure to turn traction and stability control off.