Calimili
May I ask , why do you need a CO alarm?If you sleep upstairs, high on the wardrobe or centre of the roof.
If you cook in the Ocean the I wouldn’t bother as it would be more trouble than it’s worth.
I just have a CO alarm, only.
Because of the diesel heather?
I think it's unlikely that you forget the burner on when you go to sleep and there aren't any other sources of CO2...
I would be concerned , following the experience of the OP in this thread, of an electrical fire developing while sleeping, hence the smoke alarm?