I have marked and drilled out the holes for the second rool hoop. Like the first one I used a rubber matt to mark out straight lines on the body that follow the curves in the body. Marking out a circle on the underside of the body, I then drilled a small hole from underneath on the edge of the diameter. Then measured out the centre of the large hole, fairly accurately guesstimated, checked its position with a satay stick, and made millimeter adjustments by eye when starting the hole saw, got it pretty spot on too.
The height of the hoops cannot be set yet, as that requires seat height to be determined, which requires seat positioning, which requires seats, which require steering column positioning, which requires steering rack.....get the picture?