There has to be an easier way to handle backups?
It's beginning to look very much like we need to get the "rpi wriggle" concept into the mainline Raspbian (and others) distribution. The idea is that you're just killing yourself when you do the "expand rootfs" thing and use every single last available block on the SD card.
I.e., the point is this: The solutions to your problem are:
1) Step into your time machine, go back to when you expanded the rootfs and only expand it to almost
fill the card. Of course, what I am really saying here is: In future use rpi-wriggle (Google it!) instead of the built-in expand_rootfs.
2) Using another Linux machine (desktop) or the Pi itself with an external SD card reader/writer, do the inverse operation(s) needed to shrink the filesystem down a bit.
3) Of course, if (as is your use case), the original SD card is unreadable/unrecoverable, then you'll have to do it on the image - which is more complex and beyond the scope of this post, but is doable.
And some folks need to stop being fanboys and see the forest behind the trees.
(One of the best lines I've seen on this board lately)