Has anyone done this yet? Longer-term, the solution is to expand categories with a category_tree_object_type_map. However, given serious time constraints, I'm looking for either existing code, or a solution that's quick-but-less-dirty than my first workable idea: Make a dummy object representative of each target object_type, and map to that. Kludgy, but then the rest is rather easy.
Any ideas? Anyone know offhand of showstoppers with the above idea, such as lurking code that assumes something about the mapped object?