I've been through the same dilemma recently, after a weigh bridge shock I decided to remove all of our gear and any accessories that I'd added then re-weigh the van. Jayco's original figures were spot on, they weigh the van's after all of the factory options are fitted but with no gas and water including the water in the HWS and toilet.
The other issue I had was ball weight which was also over after adding an aluminium box to the draw bar housing our BBQ, hoses, lead and other minor gear + a 150mm tube accross the front to carry rods and poles. I corrected this by adding a new rear bar with a drop down wheel carrier, now the tow ball weight is 30kg under. The only down side is the rear bar cost us 23kg from our payload, considering a carton of beer is about 15kg that's alot of beer!
I then weighed each item I added to the van and managed to cull 75 odd kg's, with one tank filled and all of our standards camping gear we have 115kg left for food clothes and bedding which is ok for us.
I was also thinking in the beginning adding a rear swing away bike carrier with 4 bikes, that would have weighed a total of 100kg! So it goes without saying that that idea was scrapped, I preferred it when my head was in the sand, this has been a painful process but it was an eye opener and great reassurance!