I like what you're trying to do and I hope you succeed, but I have some nitpicks.

Firstly, what the utility function is and what it's not. It belongs to the field of instrumental rationality, not epistemic rationality; it is not part of the territory. Don't expect it to correspond to something physical.

My utility function corresponds to specific structures in my brain.

That's it - you now have a shiny new utility function. And I want to help you optimize it. (Though it can grow and develop and change along with yourself; I want this to be a speculative process, not one in which you suddenly commit to an immutable life goal).

I don't think that it's that easy to figure out a utility function. There have been many things in my life that I've thought about and decided weren't that important, but then when I've actually tried them I discovered that I really really enjoy them. (Like, having a girlfriend, large numbers of friends, social hobbies, etc.)

You could say that that's a failure of my epistemic rationality, but I suspect that signalling is going to dominate hypotheticals that I think about but have never actually experienced. I think I would need a lot of practice in the inside view to be able to actually judge if I want something without trying it first.