Thank you! The seat unit is now in shape, next job is to make the actual seat… Not cut it to the end shape yet, still pondering! I must work on my photoshop skills!
B for me - but with a little more of a swoop on the underside sortov following the curve of the tyre.
Still undecided on the seat shape but that can wait… for now I have also made the seat base. I bonded in some alloy plates for the rivinuts to secure into. It fits rather well!