Fixed bar with parking sensors - no problem. The continuous "Beep" starts a good couple of feet before the permanent warning device (aka tow ball ) comes into play.......... Ours - 2008 Stornoway Grey HSE Auto
Tricia's - 2006 Royal Blue Beetle Cabriolet Auto
Mine - 2014 Vespa GTS 300 Super Sport Matt Black
Ours - 2007 White Bailey Pageant Champagne

Ah, much too sharp witted for me, thanks for enlightenment pressureman. Those would be similar to the kerb parking sensors fitted inside the tyres of cars used by certain other members of my family - otherwise known as expensive alloy road wheels.....apparently you stop when they make that useful grinding noise... .

Robin