Some college friends from FL had one very similar to that, a 4 dr hardtop Electra. We drove it on the beach at Daytona during Spring Break. Some jerk in a Jeep intentionally stopped in front of us crossing the dune line and we buried it up to the fender skirts in loose sand trying to get it out. Had to be towed out. Great, fun car, though. Massive, tons of room, 8 college kids in it was not a problem.
Blessed you were that it was dry sand. Those fender skirts were one of he weakest parts rust-wise on the thing and any time mud and crap got caught up in the latch it corroded the thing terribly.
I had to replace the floor boards on the driver's side too for the same thin steel reason. Had a shade tree mechanic do it. He didn't weld the floor in too securely so in a heavy rainfall going through a puddle you still got the back side of your leg splashed a little!
FReegards!