1984 Other Mercedes Benz Models Wheel alignment

first of all, if the Germans ever knew what you did ("slightly over the gvwr of the vehicle") to their Mercedes Benz they would take you out before the firing squad, I personally know they are built like a tank, but you can overdo it and it sounds like you overdid it!
At any rate to answer your question:
the car may need an alignment I am not sure, you did not send me a picture of the tires before your hall, but like a Ford with the I beam suspension, if you put too much weight on the rear tires the front tires will want to buckle under, and I don't think the shocks were the problem, because the rear suspension of the Mercedes was probably bottomed out on the stops of the lower control arm, which has nothing to do with the shocks, and the alignment of the Mercedes can only be done by a trained professional, like a BMW most alignment shops do not have the special tools or the specifications they need to properly align German cars, what it sounds like to me is you walked in to the "Price is right" and they were trying to make you a contestant, next time you go to an alignment shop to have your Mercedes checked out, make sure you ask the right question, "do you do alignments on German cars? and are your technicians German certified? and do you have special tools to make all of the adjustments along with the specifications?"