I had a look - IMO forget it.
You could cull a few .exe's in the
Caiibre folder e.g. ebook-edit, lrf-viewer etc, but 170 of the 176 MB is in the
Caiibre/app subfolder. The only place in there that you might be able to do a bit of pruning is the
resources subfolder - but it's small beer too. And for me at least the
DLLs and
qt-plugins subfolders along with
pylib.zip are definitely off limits no fly zones.
But - it's less than 180MB, I have images bigger than that
BR