He is, in fact, mortal again in the morning, and also paying sufficient attention to the world to realise that at some point yesterday he spun out of his backpack and now here it is, next to the bed, where it ought to have been. So that answers that question: he can use his spinny changing clothes powers to move things around. Maybe he should buy a bunch of backpacks and just switch between them for a functional inventory system. He wonders if those huge camping backpacks would count.
Anyway, today is Wednesday, a.k.a. day four of Peter's existence! What, oh, what wonders await him today?