If I'm parking up anywhere during the day, or overnight, I tend to keep the tonneau cover on, keeps prying eyes away. We both have Belstaffs (mine is 30 years old, hers is much newer) - they're not stupidly expensive, but still wouldn't want to fork out on replacements. If we leave them in the car, I stick them both in a drysac, and then in a
pacsafe which is locked to the seat.