I have seen many caravans in with HGV and white vans being directed to a weighbridge.
I was stopped in Bristol and directed to a weigh bridge, both car and caravan were empty,
at the time (having just collected it) years previous I was driving a six wheeled Transit and
was again directed to a weighbridge (in the Swansea area) along with a sprinkling of
caravans and motorhomes.
I always use my towing mirrors nowadays, to help avoid selection, £50 spot fine for mirror offences now as well!