I once drove a tractor off a cliff. From the top of the cliff, I could look down and see all of the stuff I had stored in it. My death box was actually up on the cliff face, so I could recover my personal inventory.
Regardless, I spent upwards of an hour building a walkway down into the abyss to collect the items from my destroyed tractor. It was a pain in the neck, went through a lot of food (because there is a damage over time penalty to going too far below the map).
After all my effort, I was literally one ramp placement away from collecting my items when I ran into an instant-death zone. Still have the whole thing set up and could show a screenshot of it. It's so incredibly frustrating to have a bunch of rare items and materials just sitting in front of you, but you die the instant you try and collect them.
ANYWAY, I digress. I believe this is a proper penalty for reckless driving. If it becomes too much of a problem for you, build walls to prevent you from driving off the ledge.
That being said, there should be a way to disable the Death Box beacon when reaching the body is impossible.