I had dealings with a college where tampering with FFE was at an epidemic level and using up significant resources that should have been spend elsewhere.
The result of a RA was several locked fire points were created. All had directional signs showing the FFE locations. Some, where there was CCTV coverage, were standard cupboards in circulation spaces, but the majority were in classrooms and offices off of corridors. Again, the office/class doors were marked as containing FFE.
All doors & cabinets were locked on a simple combination lock (only applied to classrooms and offices when the room was unoccupied). All staff carried the code behind their ID cards (always worn). Heads of section periodically 'inspected' that staff were carrying the code and all efforts were made to prevent students becoming aware.
Unescorted contractors/builders/maintenance etc, were a problem, but a separate code was given to them which was changed regularly. There was a procedure for urgently re coding the locks if there was a breach, with the priority given to securing classrooms and offices first (all of which would remain occupied during breaks until re coded). All lock codes on rooms could be changed in half a day, with a couple of additional hours for the cabinets.
It was simple & cost effective solution and the School's insurers were happy. However, the local fire safety team were a pain to begin with until they saw the details of the proposed management systems supporting the change