Is there a way to rename my cameras without messing up the BI database?

Unless things have changed recently the short answer as far as I know is No unless you had manually set the recording path to not have or use the cam name.

Ages ago I renamed a couple of cams and I did as below.

1) Stopped the BI so that it was no longer recording
2) Renamed the cam or cams
3) Find all the clips with the old name in Windows and then renamed them using a utility like Renamer
4) Performed a DB reindex then re-enabled recordings

You will lose all your alerts but hopefully it will find and add all your old clips to the BI DB.

Thanks, that is what I suspected would be the case, I may attempt this at some point on one of my two systems.

If you change only the "long name" it does not mess up the file system since the short name is used for that purpose. BI will automaticaly change the alerts to the new name.

Yes that is a good tip, but it would cause confusion when looking at the file system in the various folders