A tow bar can be fitted DIY on our cars. These people I think still do tow bars for our cars
https://www.pctautomotive.com/
Cable, socket and two relays will be extra.
I think if you want to be flash and monitor the trailer lights you need a BMW towing relay part number 61.35-8 369 019 and a wire from mmmm not sure, fuse box to light switch module I think.
I am not sure if the version of instrument cluster makes a difference, hopefully someone else can advise.
£350 or less DIY may be
macafee2