One thing I heard is to put some wire fence under the tires to get out of trouble, but taking a 20 to 30,000 pound in the sand??
I would try my class A at Padre Island in Texas, the first strech of beach is pretty hard, not like Pismo beach. It gets soft after and it goes for like 60 miles I think. I took my truck camper a good 5 or 10 miles down the beach, then drove some 30 miles further truck only.
Beach camping is nice, but it gets very sandy. We had a sand strom one day at Pismo and we had sand all over. The sand got in the air duct and we had sand for over a year comming out the dash vent.
Another thing that happen is when wind blows hard, wind gets around your tire and blows the sand around it, then it creates a small bump under the tires. Once the bumps is too thin, the tire, and camper, drops down. This is a very special moment the first time you hear the camper fall down and you do not know what happened.
The vortex created around the camper also displaced the sand and revealed some trash left over from previous campers, not very nice. Not all people do take in take out, this is a sad thing cause these behavior could lead to restriction on these nice rare places.