Thanks @Tom, appreciate all the help. After much research and thought, I've concluded the way to make this work is to host my own NAS and use it as the remote sync, and then have that same NAS backup the data to the cloud. As you have alluded to, there can be complications trying to do multiple sources-to-multiple destination syncs. It's much easier to setup and manage a hub-and-spoke topology, even though the "hub" part always makes me feel uneasy.
