I have a transporter and ive just fitted rear seats into it,(4) i have fitted quick relese seats, takes about 5 secs to remove each seat. I have put the seats onto a railing system supplied by a company called buildavan in Burnley. When the seats are removed the flooring goes back totally flush with plastic strips that cover the rails. I purchased seats that are children friendly with height adjustable belts so they dont choke children. they also have inertia built in belts so no hacking into van to mount the belts. I got insurance certificates to show the railing system and seats are all crash tested. you need to notify your insurance about this. Also did you know if you fit a window it can be classed as a window van and this increases your speed limit from 60mph till 70mph. Also i can go to my local tip to take rubbish away as its not classed as a panel van. The seats were £140+vat each and the rails were extra.