This subject has been covered many times on MF but I thought the piece on this link outlined the subject well for those that might still want some clarity.
https://www.caravanguard.co.uk/news/how-to-calculate-your-motorhome’s-safe-weight-limits-4104/
https://www.caravanguard.co.uk/news/how-to-calculate-your-motorhome’s-safe-weight-limits-4104/