I would like Mojang to remove the limits on /entitydata, making it work on players. (Though they would still need to limit a few things such as UUID etc.)
Another reason that I'm not using the armor stand thing is because some areas of the map are very steep, and the armor stand method would cause visual issues if used in those areas.
Thanks for the ideas so far everyone, I understand that it is impossible to show the actual faces. And I will be keeping this map 100% vanilla, no plugins, mods or resource packs, just command blocks. So if there is a way to just record the names of people who have died, and then show them using /title regardless if they have logged off or not then that would work.
If this feature is completely impossible to do then I'll accept that.
I prefer using my own creations, I only use other people's creations like this one if it is absolutely necessary for the map to work as I want it to, and my design works how I want it to