Don`t worry about the payload just don`t put anymore than 400ltrs in it trust me anymore in a van that size is to much.I have a new LWB connect and have 500ltr tank,when full you know it and regardless of what the payload says i think 500ltrs is to much for any van smaller than your traffic-vivaro type van.My van had it`s first service on saturday and has only done 12000mls,put it this way i don`t drive like a maniac but i needed 2 new front tyres,that kind of weight in a van that size will eat the tyres.