I'm not talking comfort, it's about health. Caves sneak up on people. 60f doesn't seem cold, but it's always taking heat from you, without end.
It's the reason otherwise seasoned spelunkers get caught and need rescue; the cave is relentlessly taking heat from you.
I have a daughter. I tell her, "911 is what you dial after you're raped. 1911 is what you should have before they try."