Most Adverts on Ebay, in the mags or on Mobile.de give the gross weight of the Motorhome..
Some also give the Tare [unladen in running order] weight.
Being as most are based on commercial vehicle chassis, the tare weight usually [99% of time] includes a driver and 50% fuel..
If you are lucky enough to have passed your driving test before 1997, you are allowed to drive any vehicle up to 7.5 tonne Gross [ aka GVW or MVW]
Example, Our Hymer 660 is 3 tonne tare, [actually 2.9 tonne without me in it] Our gross weight [GVW] is 4.6 tonne.
That gives us a 1.6 tonne payload, which is fantastic

Our old van which was a VWLT35 TDI 1997 [sprinter shape] Magnum Mobile had a Tare weight of 3 tonne but a GVW of only 3.5 tonne, = only 500 kgs payload which when going for 6 to 8 weeks wild camping/tramping round Europe was IMHO not enough..
The reason for the extra payload and loading is the back axle weight and configuration.
VW had 2 wheels and 2.2 tonne max rear axle load.
Hymer [Merc] has 4 wheels and 3.5 tonne max rear axle load.
Front axle for both vehicles is 1.6 tonne.
You will notice that when added together the axle loads exceed the GVW allowed.. thats the only leeway in loading you get.. Go over GVW or Max axle weights and VOSA will be rubbing their grimey little hands

You can be 3.4 tonne loaded { on a 3.5 tonne MVW vehicle} but have 2.4 on rear axle and 1 tonne front axle weight and you are liable to be fined for exceeding rear weight

,This is a Common occurance with M/Homes with Motorcycles on rear racks..

thats what those pads are in Laybys where the VOSA do checks...
Lots of newer Motor Homes have 3.8 tonne GVW [on 4 road wheels = 300 kgs more payload] which is great IF you passed test before 1997.
Otherwise you "should" have them downgraded to 3.5 tonne.... on the Plate so Vosa can see it on check stops.
The way we got around the worry with our VW was to tow a trailer with my Mo' bike and heavy stuff like spare gas bottles, safari room and spare 50 liters of fresh water, as you are allowed to go to 4.25 Gross TRAIN weight without a trailer licence or HGV license [750 kg max gross weight trailer either braked or unbraked] if you passed test later than 1997.
Before 1997 you can go to 8.25 tonne Gross Train weight.
Still with a max of 750 kg trailer unless you have B+E or C+E entitlement on your license..
{ This is the section of the Trailer law that is under so much discussion lately, eg you have 4.6 tonne m/h with 6.6 tonne GTW which theoretically will give you a trailer allowance of 2 tonne [ A smart car and trailer maybe ]
BUT depending on the VOSA operative you are speaking to at any particular time you are either OK or towing illegally by exceeding the 750kg trailer "rule" .
How the hell are we supposed to know if THEY don't

}
Bloody GOVT make it harder and bloody harder year by year to understand and comply to these IMHO un needed regs
