that grippatank payload calculator isnt always right, said my combo van has a payload of 550kg when its actually 775kg,
I have 500l tank in a vauxhall combo and it isnt overweight when full, depends what else you carry though, me personally think a big tranny van is a waste when a smaller more economical van can do the same job and cost a lot less
i wouldnt touch a postie van either, and I defiantly would never buy a window cleaners van,
ex BT vans are very good and imo are the ones to get