Rear seats.

Hi again everyone.
I'm putting seats in the back of the Viv, but they are gonna be rear facing right up against the driver's seat. The question is;
Will I need to drop the fuel tank out to bolt the seats in?
Will I need to reinforce the floor of the van where the seats are going?
Does anyone have any pictures or step by step guides on doing this? (YouTube is terrible for anything that isn't a VW)

Thanks again Van people.