Yes, I have been thinking about such a workaround.
Instead of saving the whole document I would save a Pose of the current figure before loading a Pose,a Light before loading a Light and so on. Far from being perfect but better than nothing.
There's something missing in my process. As you say, I should save the scene state before changing it. There are some intriguing commands like MemorizeAll. But all the combinations I have tried so far have failed.

Yarp - author of P3DO Organizer for Poser