Please educate me on allowed Van weight. (Payload? Weight? Kerb Weight)

Nebulous2

The chances of being stopped and weighed, either here or in France, are vanishingly small. Add to that the unlikelihood of being stopped with a full tank of fuel. 

That being said, running around without 60kgs of water is sensible, and consider anything else you could jettison. I've lots of spare capacity, but carry a weighty trolley jack, which could be left at home. Those bikes do seem on the heavy side as well. 

There is an option to get vans replated, although I can't remember how.

I bought an ex-mod vehicle that had been replated from 3500kg to 3750kg and we converted it into a camper ourselves. That brought some complications with insurance and who could drive, so I considered getting it changed back, but never got round to it before I gave up on it. 

Nasqueron

Are you allowing for a bike holder in that 70kg? If not, get two much lighter e-bikes, 35kg per bike is bonkers, do you pull the van with them??