An illusion to the eye cannot produce a physical effect on an opposite horizon. That is the point I've been trying to convey to you. If the sun is not really at a low angle but only appears to be because it's an illusion, then it won't be able to do the things that it can only do if it is actually at a low angle.
Why not? That piece of sky high in altitude would be observing a red sunset. Why not see what the sky sees a further distance away, as if the sky were a mirror-like thing that reflects light?
The sky does reflect light...
You're reasoning in circles. Is the sun setting an illusion or not?
If the "piece of sky" is "observing a red sunset", why is it "observing a red sunset?" The illusory nature of Perspective can't make that possible. Clouds being lit up by sunlight isn't an illusion. They're really being lit up by the sun.
But how? Don't tell me "perspective" if you acknowledge that's illusory.
So you're left with the challenge of explaining how a sun can get to an actual low enough angle to light up things low in the sky without relying on the "it only appears to" perspective explanation.
The only way I can reason it is possible is that light from the sun would have to bend in the opposite direction of the way RET says the globe curves. That's why I give EAT any attention. You've mentioned EAT, but only in terms of what some others advocate. You don't (as far as I've seen). You've hung your model on ENaG perspective. But that is an inadequate explanation. Without even getting into Rowbotham's peculiar take on perspective, it's a perceptual solution that doesn't explain physical position of the sun that could cause the line of sight required to be responsible for the phenomena we're talking about.
You can't have it both ways. Either perspective is illusion and the sun is really at a higher angle (in which case it can't be illuminate the clouds or opposite horizon that way), or perspective has a physical effect and means parallel lines really do converge in planar geometry, which I'm not buying and I don't think you do either.
If you think about what the objects you are looking at are seeing in those examples, all make sense.
Atmosphere, clouds, mountains, all reflect light to the observer.
But how can they reflect light to the observer if the sun has "set?" How can the sun be "set" to an observer (camera) on a 2000' mountain top but still be visible to particles in the atmo-whatever further in the opposite direction away from the direction of setting? That's the mystery I don't see being solved unless you invoke bendy light. Perspective can't do that.
We can both agree it's happening. The question is how? I can fathom it on a globe earth because the earth's curvature is causing a shadow that you can get up out of with elevation, even if further away from the sun. I can fathom it on a flat earth if it's light that's curving, with the flat earth causing a shadow as the sun light passes over my head and illuminates things higher up and further away. But the perspective explanation on a flat earth doesn't work.