If you’re carrying bikes on a rear rack then it needs a light board & the towing electrics.
We were coming out of Ambleside on Friday and a Fiesta with rear mounted rack had no light board. It was soon pretty obvious that out of three possible brake lights on the car, only the left hand one worked, but was obscured by the wheels of the bikes. From the positioning of the bikes I had a feeling that the driver possibly thought his right hand light was visible – it was, it just didn’t work.
Avoid main dealers for towbars, they often sub contract anyway. Make sure the fitter knows the e;ectrics are only needed for a light board, as it is the caravan electrics that need relays to power fridges & battery chargers and that pushes prices up a lot. Most dealer bars will be a rebadged Brink or Witter, so if ringing around for prices and comparing main dealer with an independent, ask the independent what make of bar they will be fitting.
You need to ask for a flange type towbar, that is the type that will allow you to fit the back plate for your carrier.