I like this idea. I think going sequentially is good, but I would change the timing method to a sum of all times rather than using the RTA of a session on its own. My reasoning being - this category is focused on the dreams and not the dialogue in-between them. I would rethink this if there were some strategy involved where you need to enter the equipment menu to customize things during the run, but I haven't looked that far ahead.

The starting conditions of this run would be a little strange. Main quest must be finished before the run begins, so the start conditions are not normalized at all. I'm interested to try it out and experiment but that's a lot of work

I think the timing method is good. I am only replying because of the ping, but I did some research, and it seems like using the first frame of fadeout as the ending time would be more difficult than using the first frame the HUD fully vanishes after the screen fades out. I assume that would work for every stage. Please feel free to completely disregard my opinion though! I just learned about this game 30 minutes ago!