DaveRo, I came to the same conclusion (I always drop down to the negative reviews first to see who tried something and why it didn't work. A guy described the exact same project and that it didn't work.)

Still thinking about it. This has been a good occasion to check out the status of equipment, such as the UPS in the closet. I just checked the manual and my notes show me that the battery in it was replaced just over two years ago. It has an LED that blinks when it needs replacing, but it might be a good time to consider it now anyway. But that doesn't get me any closer to a backup.