I'll think of something...
EDIT: Idea! When someone joins their furniture loads, and when they leave their furniture is removed! This would change the way saving works, to save furniture it would be sm_save theirname, which stores the furniture in their Steam ID, which would be accessed from the furniture save text file. I'll also have to protect it from double saving a prop.
I don't know when I would be able to get this done but I know it's possible. Until then we'll be limiting furniture.