I was nervous about leaving the top off at first, too. But, after spending all summer with both the doors and the top off my nerves have been calmed - not saying nothing will happen.
just don't keep anything valuable in it. keep the center console and the glove compartment locked nothing anywhere else (can be impractical..I know). Not looking forward to moving back where there will be drunk kids everywhere at all times
can't say how many times ive come back to my gas cap unscrewed