Otis makes a pretty small multi caliber cleaning kit. It is a pull through system similar to the bore snake but brushes and patches can be swapped out for different calibers. As far as a truck gun goes, I have a little youth breakdown Rossi. it comes with interchangeable barrels, mine being the 22 and .410. The only drawback is it is a single shot so it wouldn’t be great for defense. I have my pistol for that. The Rossi gives me the option to take birds, rabbits and other small game as well as larger game just by changing shells in the .410. It is very small and light so it wouldn’t be bothersome to carry for a long distance. I travel A LOT within my state for work. If something happens such as an EMP where I can’t drive I want to be as light as possible considering the distances I will be walking to get home( Texas is not a small state lol). I will not be looking for any fights so if something is happening at rifle distance hopefully I will be able to avoid it or hide until it’s safe. If not well I guess I’ll take the first shot with a slug and change to my pistol.