I have a small trailer with 8" wheels, flatbed, I carried lot of building materials including stacks of 5/8" sheetrock , about 1200 pounds, while remodeling my house. The car, 240D manual. With SD I would be very concerned about transmissin, I had a 300SD 81, the constant transmission problems forced me to get rid of that car.
Also, I had U-Haul to install the trailer hitch, they butchered my electrical harness nearly starting a fire in the trunk, ended up replacing the entire harness. Spend a little more and have a mechanic do the job.

Vahe
240D 77/350K