Can I turn charging on or off per guest?

You don't turn charging on or off per guest; the distinction lies with the charging point itself. If there is a point with a QR code at a property, any guest can scan it and buy credit to charge. If there is no point connected, there is nothing to scan and that guest can never charge, regardless of how trusted or frequent that guest is. If you really want to enforce who can and cannot charge, you arrange that through the placement of charging points, not via a switch per booking.