I’m not sure how or why I missed this to now, but Sysinternals has yet another handy tool, AccessEnum. From the Sysinternals site:
AccessEnum gives you a full view of your file system and Registry security settings in seconds, making it the ideal tool for helping you for security holes and lock down permissions where necessary.
This one even comes with source code, which I haven’t jumped into yet.
Way easier than using Windows Explorer to check permissions.