That part can be easily replaced with a spot weld drill, grinder and a mig welder. It is not part of the main frame rails, looks like just a support. Take that pic to a salvage yard and ask if they have one first, otherwise just get one from Benz. Just make sure you weld it back in properly and on the old marks and you'll be good to go. Drill through the outer panel only, chisel off the panel(without damaging the underpanel), grind the welds down flat, spray some weld through primer over the bare metal, drill holes in new panel(but not in exact spot, never weld over an old spot weld), weld on panel, coat with some sort of corrosion protection. Keys to making it look good are making sure the panel underneath is flat and straight, mark location of old panel so you can put new one in exact spot, use weld through primer or you will have problems later, but when welding, make sure you are clamped together very tightly(no gaps), clean weld through primer off after it is clamped in place inside the holes you will be welding, and make some practice welds before you do the real thing to test welder settings. Alot of people try to weld at too low a temp or too high and the weld either doesnt stick or burns through, so this is important.
If all this goes well, the rest should not be a big deal. From the pics it doesnt look like it was hit that hard.
If all this goes well, the rest should not be a big deal. From the pics it doesnt look like it was hit that hard.