In standard trim mine weighs 6100 kg, the only item not present when weighed was the bench seat from the rear, all the drop sides and the canvas were still present. I would imagine that the manufacturers plate weight of 6600 kg refers to the variants fitted with a winch and or tail lift. SV Tech told me of another GS they recently down rated that was presented for test with a weigh bridge ticket of approx 5500 kg, apparently it had been raped beforehand! :-D
OK, I'm still under 2000 kg, but I have gained permission by making a statement of intended use, this statement coupled with the vehicles special historic nature gained the approval of VOSA to down rate and run without tacho.
I shall be taxing it and using it as a private heavy goods vehicle. The minimum 2000 kg payload is not actually a legal requirement, it is only a VOSA imposed recommendation, therefore if you provide 'good reason' and make a written statement of intended use, permission will be granted.