If you follow the close scene rule then those parameter nodes will be deleted when you restore a previous scene view.
I think we can define a clear line: we restore content of all display nodes and view nodes (and potentially hierarchy nodes). If we limit the types of nodes that we support then we can ensure correct save/restore behavior. The behavior will be also very simple if we don’t support adding/removing nodes (we just hide anything that we don’t want to show) and saving/restoring content from files (all saved/restored data can be stored in xml string).