I don't know if you can add the action to hide bodies in description.ext files or scripts, but I think not.
I think if you need a unit to have this ability, it needs to be declared in the config.cpp.
I don't think setposing your bodies upwards will work either, you can setpos them up, but they fall to ground again afterwards.
Actually I tried this with a Jeep, I setposed it from the ground to 1000 m, using a trigger.
Of course, it came back down again, and....... it was undamaged.
I even tried it with myself sitting in the jeep as driver, both I and the jeep were able to drive away once we got back to ground level.
If you do this with a soldier, or yourself, both will die.
Although I have been unable to setpos a soldier, dead or alive, partially or completely, under the ground, I can do this with other objects..... i.e. ......the Jeep.
You can even have yourself or another soldier in the jeep at the time.
You can bury a jeep completely, but as long as you remember its location, you can still get in........and drive away.
I know, I know..........I have too much time on my hands.
Planck