I tried (after devmap) to enable cg_drawbbox in few mods that I thought had Unlagged technology. In CorkScrew and Alternate Fire, the variable seems to do not exist. In Unlagged-RR, instead, it does exist, but it strangely seems to have no effect. Maybe when they ported Unlagged technology to their mods, they took only the "core" part of it, and did not import such "extra" feature?
I've found a download for the Unlagged mod:
here there is version 2.01.
Install it, load a map with devmap and set cg_drawbbox 1. Enjoy hitboxes!
Does that help with your tests to check if a player has got a base of 30x30 or 32x32?
I'd suggest to create a test map with three passages, wide 32, 31 and 30 units respectively (a single corridor made with sections becoming more and more narrow maybe?)... then try to pass through them and see what happens. Then, check if bots pass through them, too.