Hey so I found a way to just backup to a patch 4 days ago using this guide: https://steamcommunity.com/sharedfiles/filedetails/?id=1086279994
You can go back even further honestly and just go back to a few weeks ago before the Rockstar launcher was a thing 😀
The depots you need from https://steamdb.info/app/271590/depots/ are 271591, 271592, and 271594. Just drag and drop once you've downloaded and make sure to disable updates and you're right back in Los Santos.