All you need is an angled bit of tube to mount it on!
https://www.ebay.co.uk/itm/Universal...UAAOSwt8JZ3kIM
If I remember correctly, Dad started with one on the caravan drawbar but later changed to a mirror arm that dropped into a tube mounted on his tow bracket on the car. The tube had a slot in the end and the mirror arm had a pin through it to locate in the slot. The mirror above the towing hitch could be seen through the interior mirror on the car, allowing the driver to aim accordingly. When not in use, he stored it (the truck mirror) in a couple of expanding clips in the top of the boot. It took only seconds to fit and remove.