As much as people seem to dislike the Marlin's hammer block safety, I like it.
With the hammer down and the safety on, it's beyond unlikely that the gun will go off, even if there's a round chambered.
You can still keep the safety off and the hammer down, old-style, when hunting on foot. But the safety provides a positive lock when you absolutely want to keep the gun from firing.
That said, I have a single-shot Ithaca shotgun, break action with a levergun-style lever to open it, and a rebounding hammer. It has no safety, and there'd be little sense in carrying it around without a round in the chamber.
So a similar action, with a hammer block safety in addition, should be good enough. That doesn't mean I'd point the gun at someone, or that I'd be comfortable if my hunting buddy swept me with his gun, but that'd be true if the chamber (supposedly) wasn't loaded, too.
All of that said, if the gun is sitting in a safe, I'd just stuff rounds in the tube and keep the chamber empty.