A quick workaround that immediately comes to mind is to use a trigger which runs once for every unit on the battlefield by having the condition field to be: {_x exec "removalscript.sqs"} forEach thislist
and then writing the script such:
_p = _this
#START
@((!(alive _p))||(getdammage _p >= 1))
; When the unit is killed...
_randwait = (random 120)+60
; Pick a random time to wait
~(_randwait)
; Wait that amount of time
?(!(alive _p))||(getdammage _p >= 1) : deletevehicle _p; exit
goto "START"
; Check that they haven't respawned or come back to life and if not then delete their body and exit the script, otherwise go back to the start.
I just threw this together now so I can't guarantee it'll work but give it a try, or just search OFPEC for an already existing much better script.
Cheers.