Well, I thought about it for a bit last night, and figured I'd start filling it again. If the liner popped out, it was going to anyways and this would give me a head start on draining it haha.

So I filled it from about 8PM till 11:30. The pool is up to 11". I couldn't get myself to let it run all night unsupervised. I started it again at about 6:30, and will watch it every so often to see how it's doing.

Now the water is climbing up the walls, pushing the liner directly against the wall on the ends. This I think is a good thing, hopefully, causing the liner to stretch on the sides. Perhaps it's now a difference force being applied against the liner (outwards against the wall, instead of down against the floor).

I have about 1" overlap left in some areas, very small. We will see!