You could possibly do that, however that is more work then most people would want to do. (No offense to anybody) Even I would shudder having to do that.
Not that much work. IDK about you but I have a save right before
Spoiler liberty prime takes his walk across the Enclave's backside towards PP
so
if I had BS I'd test it out at the very least, just run through and complete the quest, wait for BS to kick in and do whatever it does, huzzah huzzah huzzah I'm a hero, reinstall/fake patch and go VATS crazy in the new content. Fully operational VATS is a requirement for me, and if it means having working VATS or a lvl 30 cap, I'll take VATS.
Including game time I'm talking maybe 20 minutes, and that is with cleaning my registry and two PC restarts(one with uninstall, one with reinstall).