its through the floor with BIG spreader plates - looks ok to me!
You're right about the hinging, but it might be a problem with the top seatbelt mount not being properly fixed.
I'm going to make some "socks" to cover the frames so they are a little less conspicuous.
It's all removable to I can return it to "original" when the kids are bigger. I also decided NOT to cut the original wood as I know if I was restoring the van after me, then I'd want the original still in one piece - after all we are all just looking after our vans for the next owners!
Rupert
www.littleyellowcar.co.uk