With my 19.5" tires, I really cannot air down enough to make a difference. This does limit where I can travel, but does not exclude me from beaches. Since we have off-road toys with us, we go as far in as conditions permit and set up camp. The toys then take us places where we would never reach with a camper.
That is an interesting twist on the story I heard about those campers going through the tide - Maybe someone was trying to protect the ignorant. We annually head toward the south eastern edge of CA and have not been out to Pismo yet.