I finally synchronized a borrowed chain-saw, electricity (for the electric chain saw), free time, and daylight to allow me to climb onto the roof of the garage and cut off the two main trunks of elm that were still up there.
Quite a bit of physical exertion was required, though it only took about an hour. There were a few precarious moments, not knowing when and how the main trunk would fall or roll.
Now that the roof is clear, a few spots of minor damage are evident. I’ll need to get up there and patch a few places sometime soon.