Surely the simple answer is a latch which can only be opened or locked with a tool that has 6' of 'COWL IS UNLATCHED' red tape on it, and can only be removed if the cowl is locked??
Let's call it a 'key'...
Even my automatic car has an interlock on the ignition key, it won't come out the lock unless the handbrake is on and the gear selector in 'Park'...
