Thank you for the replies! I just didn't want to go wandering the wilderness and die with a house deed in my backpack and lose all my hard work.
To clarify, runebooks cannot be directly stolen by a thief unless they are in a bag, and the thief steals the whole bag. (make your bag weigh more than 10 stones and they can't steal the bag)
This is a bit silly - I routinely have 2 deeds in my pack, just in case I happen upon a great spot. I die all the time...