I have a different perspective of an observer's observation conclusions of Saturn's rings - presuming that the observer stands sufficiently far away from Saturn.
Regarding Saturn's debris, if one was on-plane with the moving debris, one wouldn't think that the debris moves in a straight line if one had binocular vision. One would see that the debris was moving in a circular path along the surface of an an imaginary plane that was straight-in-line with the observer's position.
And, what if I presume the observer is closer? Is your presumption more valid? Not at all, but you have further validated my point. It's all about perspective. Thus, Homer gave us 2-J-3.
So, a claim of an On Plane motion with a camera that is not On Plane is a guess, no matter how 'educated' the guess. If someone challenged your claim that Kim was On Plane and required proof, you would place the camera On Plane to provide proof.