I don't like hunting with a fouled rifle, especially on a long camp-out hunt that may last a week or more. Not one to pop caps either. My ritual for loading for a hunt is to clean the rifle within an inch of it's life, then clean it again with alcohol. (no, I don't mean cleaning it again while drinking alcohol)(that comes next) De-natured alcohol. The rubbing stuff has too much water in it. With a cap gun I remove the cone, clean it out with pipe cleaners and alcohol, and run the pipe cleaner through the flash channel. Might even take a walk out to the garage and run some compressed air through it. Let dry for at least an hour, after cleaning with dry patches. That makes for a 100% reliable rifle.
As far as overnight storage in the camper or tent, with a flintlock I wad up some paper towel, jam it against the touch-hole, and lower the cock and flint down on it to hold it tight.. Cap gun, some paper towel between the cone and hammer will keep any moisture out.