I have good news! This has been done!
I myself modded this a bit: I swapped in TagSEarch for the default tagger, added x-plore (both by Tobias Beer), added Intellitags, HistoryPlugin, FootnotesPlugin NestedSlidersPlugin, PreviewPlugin (with a Side-by-side view, added in the EditTemplate), SimpleTreePlugin (also by Tobias Beer), and a few other small plugins.
Mine is here:
https://drive.google.com/file/d/0B300Uw4EAaNoNzJ5ZGNNeC1KdTQ/edit?usp=sharing
They both have features that the other does not, but they are used in nearly the same way: <<macroname roottiddlername [parameters etc]>>
TreeviewPlugin has more visualization options, is significantly prettier (with lines, showing the hierarchies), whereas TagsTreePlugin (esp the updated one) has more options regarding filtering/sorting the tiddlers/tags (I myself don't quite understand some of them, like how to use the sortField one.)
Now, this isn't EXACTLY what you're looking for, but if I'm understanding you, it's a significant step in that direction.
What do you think? If you mod some of those more toward what you're thinking, post your results here, I'd love to see it.