the police dont pull u the ministry do, they just have the police there in case u kick off, if you get pulled whilst out driving and it looks ok then most copper will just leave you alone,
if u get pulled they will take u to a weighting station to get it confirmed, if they do and you think you are over weight, start emptying water out of your van, by switching it on and the water should empty out as u r driving lol
the one thing i woulld do is repalce you shocks on your van as this will help with the weight
the chances of you getting pull are slim, unless u have an accident and they take the van