When you have a model file which takes long to save, the AutoSave is not really ‘transparent’ and freezes the UI. This can be an issue when you are in the middle of an interactive tool.
I would propose that AutoSave only triggers when you are in the Selection Tool, that is, not within a native tool (like Move, Rotate) or an extension interactive tool.
Another feature of AutoSave would be to version the model file with the date and keep the last X versions (X being defined by the user). The mechanism can still use a skb extension to allow Sketchup to identify them as auto-saved files. Then, when you crash Sketchup, you are presented the choice between the last auto-saved versions.