Im losing myself in an inch of water!
I need to transform the origin of the canvas on my demo and pin it, till the end of the document, then reverse everything when I scroll again near the very top.
To fake the perspective I used a clip-path (even I guess that using something like:
transformOrigin: "-500% 50% -100px",
rotationY: 25,z: 500 m
May work even better for the cause.
Btw what's the problem of the jumping pin?