I've done alot of towing over the years. Mostly towing race cars to meets, the odd caravan and box trailer. Never really found it a problem, towing a car trailer is probably the hardest thing I have done. There are many things to consider when towing a car, the type of tow vehicle, fwd, rwd and that will also dictate how you load the car to be towed as well, as the nose weight balance has to be right.
In the first couple of weeks towing I soon realised the benefit of a good trailer design and how handy the 'snakemaster' kits were!
Reversing is an art, something not to be rushed and comes with experience. I find longer heavier loads easier to manipulate than a small lightweight trailer.
As for the biggest thing I have towed was probably the trailer itself. I borrowed a trailer from one of the directors at my previous company, he had an all singing, all dancing tilt bed affair. It was big enough to fit his yank Ford Galaxy, so was pretty big. I borrowed this to collect a Mini of all things! :amuse: Other than that it was my own trailer carrying an Audi GT Coupe race car.
Longest journey for me was doing a round trip of around 600 miles picking up a car. Had a puncture on the way back, not nice!