Finally gotten back to work on this thing.
With the dropped floor , if I mounted the third seat directly to the floor visibilty from that seat will be very poor.
After some thought I came of with the Idea to build a raised platform to mount the third seat to. Didn't want to waste the space so I decided to build the platform to fit as a cover for a drawer.
Shot it with some primer.
This will mount to the floor beside the side entry doors.
Sourced the drawer from the Mac man.