Good thought, I might do that for now.
ETA: It doesn't seem to be working well. There was no option in the online tree to add an unrelated person to my tree so I tried in FTM. There is an option for it but when I synced my trees so the new "person" labelled Unidentified Photos would also be added to my online tree, it doesn't work. It says the trees are synced yet it hasn't uploaded this new "person".