When we lived on Long Island our regular camping spot was the beach at Montauk. Used to pull the 34' TT out into the soft sand with the Suburban. The trick is to air down the tires on the truck AND trailer to 15 psi, 12 if the sand is really soft. Use 4WD LO range and go slow, You can start/stop with ease.
Avoid what looks like hard-packed sand down by the waterline, if you hit a soft spot it will be like quicksand and 10x harder to get out of vs. getting stuck in dry sand.
Way2roll, we have been woken up a few times to water under the trailer when storms at sea combined with a full moon to create a tidal surge making an unusually strong high tide. Gotta have insurance, because if you have to evacuate, you ain't taking the trailer with you...
All that said, there is nothing like camping on the beach! The memories are truly lasting, since you never ever quite get all of the sand out of the camper...