Hi Phil.
You say: where the wave function collapse is an illusion of our own experience.
Yes, because it creates a subjective information, we choose what we want to get or what to measure, and we can even change the past, maybe also the future? This change of the wavefunction is lasting just a moment when we extract the information.
You also say: The only viable solution to the measurement problem is to replace materialism with idealism. The observer is not just something different, it is everything. Before quantum theory philosophers proposed various types of idealism: subjective idealism, objective idealism, transcendental idealism, etc. what we are considering now is best termed quantum idealism. This is not some religious or spiritual philosophy. It is pure science.
It is amusing that this is also what Wheeler said. He made the subjective measurement or illusion central, and this lead as an extrapolation to the many worlds scenario, that started with Wheeler also. Keith do work with this.
He put the observer as central to creation simply.
This is the same as the way time is generally treated in our subjective lightcone. But that time vanish in objective perspective, showed Einstein. We can ignore it. But what is then left of time? Just a vector that pushes on the flat spacetime? Or can time be a part of gravitation and also code information?
Why do we struggle with all these possible ideas? How many different ideas are 'out there'? How many degrees of freedom? Maybe something has to fuse them together into 'lumps' or 'boxes'? In cognition that something is chaos or noise, and what we extract becomes then a signal. Note that we as observers are a part of that signal.
Also, if we want a change we must increase the chaos first, climb the latter of Lorentz boost... increase the speed or acceleration etc. (I often feel this is my task here on Earth).
I also much like Matti's view of consciousness as an 'inbetweenness' or a different ontology, what the Lorentz invariance also can be seen as, when we consider fields.
Friendly, Ulla Mattfolk.