I think I've come across something of a fix, though sadly I think this will probably only help me and not others with similar problems relating to the fixed parallax origin issue.
What I've been trying to do is generate an asteroid field in the background of my game.
So what I do is basically create a few thousand objects at random(layoutsize). Then I scaled each object based on the parallax value of the layer it was on. This caused more "distant" asteroids to scale down and look appropriate far away.
After searching through other older threads about similar issues I came across https://www.scirra.com/forum/top-down-fake-depth-3d-effect_t81087
By using buddy40's method of setting the background layers to a different scale, I've achieved the parallax effect that I wanted, while mostly maintaining the correct visual positions of asteroids.
This does mean that I might need to use a wider range of coordinates for my background layers to compensate, but otherwise the problem (for me) is largely solved.