Good one.
No, like most things that I design the idea comes from what I have on hand and the will to make it work.
Made the front end easy, hack off the bike and use as is. It wouldn't quite fit so I slit the square tube, bent the 4 pieces outwards, inserted the tube and heated and then clamped the pieces onto to the round tube. It's a clamped sliding fit that allows for in and out adjustment.
Ron