Order WOMO as a van, reach the load limit?

Hello together, we family 2 adults with 2 children eight and ten years would like to order us a box van with set-up roof. With awning and some small extras we are already at almost 3270 Kg. So we still have 230 kilos of extra charge the people are not even included there. minus the co-travellers we would still have an extra charge of about 100kg for bed linen and food. Is that enough or how do you do that? We have decided a 6,36 m with long beds and set-up roof, because we do not want to do without the sleeping comfort. Then rather save at another point… Load up or a camper we do not want to take advantage of because we want to use the advantages of a box van. In particular we are more for short trips like e.g. city trips… I think that in general with box vans the extra charge especially as a family with children shows itself rather as very difficult. How solves this problem? Or is this generally so and one takes the risk to drive something overloaded? I am very grateful for every advice. Lg.