I think the same but i found nothing. I flashed a debloated rom for the 10.1 and now have 1.2GB free on system parts. I used titanium backup to transfer some app from data to system but it's boring. But it's nothing compared to my MicroSD card memory
I did transfer some apps over as well, or in reality can remove them because they sit on the SD partition because of updates (really wish it would just update to system by default). I know moving some updates over just screws it up, let alone just moving screws up the icons on the desktop portion.
I don't have a de-bloated rom right now. The way I see it, its being used or wasted at this point. Apps don't seem to be slowing it down, though im sure a few are running in the background, but nothing that has hampered battery life like my previous Nexus 7 (2013). This seems to do much better at not wasting power. Guess im not being as picky as I use to with random apps chewing up space.
I would of jumped all over a 32GB edition from the get go. Paired with a 64GB SD card, its win win. Even now it is, just can't install everything I want to in 1 go since most apps still are stored locally on the main internal SD Partition and can't be transferred over. I can live with it, and im sure someone will figure it out. I know I use to do it with an old phone that had, next to no internal memory (a loong time ago). PITA to update, but well worth being able to use the phone.