Yea I always forget to lock my backpack, backpack!
I've learnt that if i put things in my vest, like medkit, mine detector, ammo and only have FAK's 'First Aid Kits' and smoke in the backpack then the sticky finger thieves cant get the most important items.
But lets say I'm a HAT and have all my titan AT's in BP and forget to lock it....
Great idea, cant see why it wont work, if they can have your last played load-out, just add the lock state to the list.