This time a quick and dirty update as was the visit to the car.
Around 6 hours was spent with these "achievements", but one can only wonder why and how it took so much time...
I cut a corner out of the rear rail...
Suzuki GSXR, "aviation style" in appearance, gas tank cap/lid.
Quite nicely made, aluminium, 110mm OD and came with a rubber seal and locking mechanism.
I'm going to put that at the rear of the car and then connect it to the "tailor made" gas tank.
Should be interesting to engineer.