Not sure I follow the unladen weight part?
I read this
T5 & T6 Speed Limits - Jerba Campervans and determined that because I have van/side windows I'm fine at the normal speed limits. My van is a T32 LWB and weighs more that 2040KG.
Since then I've been through dozens of ANPR controlled roads at ~70MPH and never had a ticket.
So on that basis I don't believe the weight is relevant.
Consider yourself fortunate then. Other folk have been pinged. They have said so on this forum, and have only avoided the ticket by being able to prove dual purpose and weight by showing V5 and paragraph from the refs.
It’s like with any speed device, one day you may go past it and it’s loaded, or that car you’ve just passed might just be an unmarked police car and the traffic officers in it might be having a lean day.
If you want to chance your arm on the law of averages and that there are not enough Police Officers out on the roads, best of luck. You might get away with it forever. But then again you might not.
If you have a Kombi, and your mass in service as indicated on your V5 states 2040kg+, simple fact is that you can not pull the “dual purpose vehicle” card out of your sleeve as per determination in construction and use regs.
My Kombi is over 2040kg, so I do my very best to stick to the 50/60/60 limit. Granted sometimes I go over it, who doesn’t, but when I do I know I am running a risk. You could try and baffle the bobby at the side of the road quoting a paragraph of the regs they may not be overly familiar with. They’ll still ticket you and tell you to prove otherwise, and I’d like me your V5 reads over 2040kg, you are buggered. If you are under, appeal the ticket send in a copy of your V5 and the appropriate paragraph, it’ll be cancelled.
@Thogg has given very clear guidance over a couple of years on this, and as an ex-Roads Policing Officer, I am inclined to listen to him, and as he is leaving the forum, I thank him for aiding us to stay on the right side of the law, and help us maintain our perfectly clean licences.