Unfortunately, the only hitch available for your van has a 1-1/4" receiver. The Rola Enclosed Cargo # 59109 will not work for you since it requires a 2" hitch.
Instead, I recommend the 20x47 Reese Cargo Carrier for 1-1/4" Hitches - Steel - 300 lbs # 63155. This will work great with your 2001 Mazda MPV dx. It is possible that you could open your hatch with the carrier on, but I am unable to verify this. Once you add cargo, it could further interfere with your hatch.
Check out the video... view full answer...
I checked with Curt and the Curt Trailer Hitch Receiver - Custom Fit - Class I - 1-1/4" # C11805 you were looking at is confirmed to fit all models of the 1983 Mercedes-Benz 300TD, so it will fit your sedan just fine.
I included a picture of the # C11805 installed for you to take a look at. view full answer...
I do have an option for you but there aren't any custom fit towing mirrors for a 1980 Mercedes-Benz 300TD. The only option for this vehicle are universal fit mirrors, for which I recommend the CIPA Universal Towing Mirrors part # 7070-2. view full answer...
The TowReady trailer wiring harness that you referenced, part # 119179KIT, is one of three powered taillight converters that will fit the 1985 Mercedes-Benz 300TD wagon. All can be seen on the link at right. This 4-pole harness is shown in the linked install video, and is one of the items needed to install a trailer brake controller like the excellent Prodigy P2 # 90885.
I suggest you take a look at the linked article on brake controllers; this will further explain why I recommend the... view full answer...