If anyone is interested in this, all you need to do is instead of holding a single texture, hold an array of textures in my plugin and somehow expose the Spout sender name association. Could probably just do “UE4 Sender #X” where X is the index into the array of textures stored. Annnnd tell the updater about the array of textures instead of it updating just one.
I’d do it but I’m incredibly busy atm.