few things, first off.. AIR DOWN not up. Floatation is key. 10-15lbs, i've seen many people stuck on even entrance hill just not airing down.
I know you should drop air pressure. we just don't like taking the time to air up before hitting the highway home. last time we went the sand was a bit dry and I thought we would have to air down but like I said with a little finess we made it in and out. but we mainly drive the truck in to carry tools, grill and food and just park the truck by the beach and I don't think I ever walked down to the water. plus we haul the moto in because it is a bit loud.
I been there after a good nights rain but, I don't think I have ever seen that much water in the riding area. I have heard it get that wet in that area though.