I have been through this crank bolt stuff with Porsche - ~250ft lb area. Fortunately Porsche make a flywheel lock tool which bolts into the bell housing and picks up the ring gear teeth. Makes the whole operation very easy, no danger of damage etc. And they are only $25-30 IIRC. I suggest you check for MB providing such a tool somewhere. I hate talk of sockets engaged and hitting the starter motor!!!
jp