Solution implemented! The freezing UPS problem I devised a solution for is now fixed. Yay! And I did it exactly the way I had planned. That hardly ever happens. :)
The first photo below shows the shelf I installed, with the bottom of it being 10.5 feet above the garage floor. The hangers that the 2x6s are sitting on were that leftover garage storage kit that I had. In that first photo, between the two boards and a bit to the left you can see the 4" hole I sawed through the garage ceiling. There's a matching hole in the second floor's floor. The second photo shows the UPS all wired up and running. I'm writing this post on a computer powered by that UPS. It works!
The primary purpose of this project was to locate the UPS in a space that is temperature controlled – a sort of Goldilocks temperature, neither too hot nor too cold. The barn's garage suits that bill perfectly. In the winter it's heated, never getting colder than 65°F. In the summer the excellent insulation in my barn plus the thermal mass of the 8" thick concrete floor keeps the temperature below 80°F most of the time, and the highest it's ever been is 84°F. That's well within the UPS's operating temperature range. My freezing UPS problem should be gone, and hopefully I didn't introduce any new problems while doing that.
There's a secondary benefit though, one that I hadn't even considered. The UPS has rather loud fans, and now they're running down in the garage where a bit of extra noise will mean nothing (as there are many noisy things down there already). That means my second floor is now back to it's basically noiseless state: nice and quiet for working, no noise to mess with my music.