In my experience, dooley's first correlary to the golden rule is what I follow. "Do unto them before they do unto you"
That being said: In over 15 years of bike touring I have never had to use a personal protection device.
I camp in public camp grounds, People's front yards, city parks, and have "dived in" - that is disappeared onto the brush.
This summer I am going to Norway with my bike. We will be camping there. Interestingly, camping is permitted there almost anywhere - according to the guide book on Norway. Considering the price of hotels, my family will be doing a lot of camping.
Back to the main topic: Carrying heat. I carry a large pepper spray bottle. In Upper Penn Michigan, bears are not uncommon. To use a gun on a bear will only irritate it. When I dive in, I use a device to hoist my panniers into a tree to make it difficult for animals to get to my food. I got that at a camping store.
I carry a knife - for fishing, and a shovel for digging holes to poop in. The fishing knife or the shovel could be also used for protection. However, I also have carried a .22 cal auto. Recall, as I have said, I have never needed it.
Remember, the best method to avoid problems is to camp out of sight of the idiots who "just wanting to have a little fun".
If you do have any weapon, remember, it is usually "illegal" to have one in a state or federal camp ground. But then you rarely need one there.
On the other hand, the Natchez Trace is a 400 mile long Federal park. Thus, even police in Mississippi can have problems carrying a gun in their auto in that park.
I hope that this adds to your indicision. If it really bothers you to camp, for fear of others, then you are better off touring and using motel/hotels.
Tom