Mass in Running Order - 2019 Mercedes Bourton

Have a new AS Merc. Bourton with premium pack, listed in AS literature as 2980 Kg MRO, 520 Kg user payload, Max laden mass of 3500 Kg. Just been to weighbridge with full tank of fuel, 75% water in tank (no waste water), 75 Kg driver and approx. 150 Kg. of user payload - Weighbridge ticket states gross weight of 3335 Kg. Suggesting remaining user payload of 165 Kg. 150 + 165 = 315 Kg of user payload, 205 Kg short of the 520 Kg. stated by AS. The fuel and water total 105 Kg. still 100 Kg short of AS claim. 
Anybody throw any light on this?  Is the weighbridge ticket wrong or is AS over stating the payload? 

In recent years the MIRO figure has changed. In 2012 it included 75% water,, fuel, gas and driver. A couple of years ago it was changed to omit some or all of these which were separately mentioned as "essential habitation equipment". Have you got the right figure? 75kg driver will be most of your 100kg discrepancy. Not sure how a driver is habitation equipment even if essential!

MIRO for a current Bourton is stated as including 90% fuel, driver at 75kg and the mains cable. The additional weight of the premium pack and fresh water  are not included in MIRO. This may be most of the "discrepancy"

This is exactly why we had to change our Corinium Duo, we had loads of payload but back axle was overweight. When we bought our new Burford Duo which was fully loaded with extras I made the dealer weigh it before finalising deal and although figures weren’t as published we had plenty of payload and axle loads left.  The axle loading need to be checked also