If there was a worthy thief running around I would caution that this was a terrible idea.
EDIT: It's actually a good idea. Just bad choice as a good thief will take your most needed items easily. I have multiple containers for this sole purpose.
If a thief steals your main backpacks it doesn't really matter. I see this as being more useful for bags that you store inside your packs...but nothing preventing:
I remember when the savant Lich Rathaneus had to fight Chudo the Warmaster drow thief. He had the bright idea of cabal naming his backpacks. I had somewhat the same idea on the past, with naming my mindflayers, only to have F00x teach me that he could disarm and sac them the same. So you know what happened to the backpacks? Chudo just pilfered them and saced them.
Hum... perhaps it wasn't the Lich, perhaps it was the Mad gnome Psi Knetic Miria.
Bottom line. Do this to a cabal container or you know what. Else there will be a hole in your purse...