Hi Simon,
Sounds like the installer needs to recalibrate the rear sensors to compensate for the towbar.
The Camera/sensor can malfunction when dirty or very wet, but worth checking with Hyundai dealer in your area if there is an update to software to make this less sensitive.
The Satnav will be a harder fix. Built in Satnav (in all brands) are notoriously slow to get updates. The software mapping is usually supplied by a 3rd party. By the time the third party gets around to doing an update then communicates that update to the manufacturer and eventually shared to individual dealers you can be looking at 18 months or more out of date.
For example, My previous car a GM product (Holden) still had the wrong speed limits in some areas after 3 years. My 2017 i30 appears to use the same maps and some limits are wrong as well.