I have vanquished the sky in bedroom 2 (the north-west one, for some reason I think of this as Swanson’s room, even thought that has not been discussed).
Lessons learned:
8 feet 4 inches is plenty wide when it comes to 2 mil plastic sheeting
Use more masking tape when attaching the plastic sheeting to the walls, it’s worth it
Never, ever paint over popcorn ceilings, it’s like kicking a puppy, except over a much longer time horizon
Use more water. I know you’re afraid of messing up the sheetrock, it’ll be fine.
When you use more water the mess you make is much more satisfying