On my 1982 240D access to the crank bolt is pretty much impossible....in fact I can't even get my hand between the plastic fan shroud and the engine. I just jog the starter to adjust the valves. I don't think you have to have the cam lobes pointing exactly 180 degrees away from the valve to get an accurate adjustment. It usually only takes 3 or 4 jogs to get a reading on all of the valves. You just have be careful to keep track of the ones you have already done, because with this method the adjustment order will be random.

My $.02 worth.

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold