I had a trailer hitch installed on my 240D/77 a long time ago, I do have a small flat bed trailer, real small with 8" wheels, with that trailer over the years I carried tons of building materials to remodel my house.
One word of warning here, the hitch came from U-Haul, and they installed it for me, DO NOT let these jokers touch your car, while installing mine they butchered the electrical harness causing continuous electrical problems over the years and about two year ago I nearly had an electrical fire in the back of the car, fortunately it happened in MB shop and they replaced the harness from an older parts car.

Thanks,
Vahe