Am i reading the manual right that you have to have the spreader plates for the rear fixings at least 10cm square and 4mm thick?
Steve.

Im sure most people say they have used large repair washers for the job

M8 skt hd bolts & nuts that came with the seat runners with large diameter washers on the underside of a steel floor were OK at SVA.

I have an ali' floor and the rear bolts dont go through any part of the chassis. So, im reading it that this is what you have to do. Maybe not then.
Yours,
confused