One of the most important tools for working on our high ceilings has been the sets of scaffolding on wheels. I bought these at Harbor Freight with a coupon so each set was about $200 with tax. I first bought one and then when another coupon was published, went back and bought another one and they have been handy tools to have.
I had to use the double scaffolding to get high enough to fix the bird holes.
The demolition guys who helped me finish the high areas of the cathedral ceiling used the scaffolding too.
We have only been using one set to put up polyiso the other is disassembled for now. Both will be used again when we put up the trim and paint etc.
Another useful tool from Harbor Freight has been this ratcheting holder. I could not find it on the Harbor Freight site so they may no longer carry it. They have a ratcheting pickup truck holder which might work the same, but this one has two pads, one on top and one on the bottom that hold the panels to the ceiling. The ratchet gets stuck sometimes and the pole doesn’t tighten as well as it used to, but overall it has been a useful tool. It was also on sale when I bought it for about $10.