Glad to hear you're still thinking about doing the other run :)
You say you can skip the undine.
i played AoS today again, and i got reminded to a certain trick.
namely, when you enter the castle and take the lower path down to the 'river' where you get the flying armor sould.
When you get the soul and go 1 screen o the left, you see a pltform above you, not reachable.
Apperantly though, when you jump towards the wall, and then jump as soon as you touch it, you can do another jump. i tried again today and couldn't do it, so i gave up.
later, when i got the double jump, i finally managed to do it again, but even without the double jump! (i believe)
so, i don't know if you even need the double jump to do it, or you can do it without, but you can certainly do it.
this way, you never need to visit the inner quarters.
i'm curious about how you're gonna skip using the skula though :)
and if your way of skipping the undine is not what i mentioned, then what is the trick if i may ask?
Persona is planning on doing a no-damage run full-map for this game, so it'll be great to trade these tricks