I trust math and always have; it's the "anti-conspiracist" mathemeticians I doubt. It's amazing how many people trusting contrailscience.com are trusting the mathemetician automatically as if he was math. Very disturbing and, as you said, instructional.
You're doing it right -- I'm flying (no pun intended!) on the seat of my pants to try to determine and explain why plain common sense makes me so certain that good folks are being deliberately deceived. You're proving it -- I'm just shouting it.
The math shall set you free! ;^)
47.743116,-122.194077, altitude approximately 80 feet, +/- 15
Heading: 246 degrees (north being 0),
Unknown field of view of camera, I estimate 100-200mm, not sure if those photos are cropped.
Time: 5:19, 5:20 which correlates from cargolaw.com fixed camera image (5:15pm) of same contrail from LAX.