I respectfully submit that even though you say you are a trusting soul, that you are considering the weight and the liabilities of a gun on your journeys says something else....

I grew up around guns. I also grew up in the mountains, around snakes, bears, and all the other critters my family hunted. I am not afraid of any of them - somehow I have made it into my forties without being bitten by any of them, even the rattlesnake that was coiled at the foot of the slide in the backyard when I was playing on the swingset. (We killed it with a hoe.) We only had guns out in hunting season. That's what they are for. Hiking and fishing, we left the gun at home.

In practical terms, you are better served by a good hiking stick or poles, and a holster with pepper spray. You will not be arrested for carrying it without a permit. You won't need to purchase or acquire any sort of permit at all. You won't need to aim perfectly if you are using bear spray.

If you are in a national park or forest in California, and you see an area that looks like it is being cultivated... you leave, being mindful of where you step and as quietly as possible. A gun won't do you any good. If the marijuana growers are present, they know you are there and have you in sights.

If you see a snake, you avoid it. If you are careful of where you put hands and feet (don't stick them in crevasses or holes out of sight) and don't step on them, they won't bite you.

In bear territory, you follow recommended food storage regulations and practices for the area you are in - do not assume you can hang food in Yosemite, for example. You follow grizzly precautions in grizzly territory, and worry about food storage for the most part in black bear territory.

Statistically speaking, you need to worry most about insect bites and domestic dogs. Deer kill more people than bears do. There have been no bear related fatalities in Yosemite - but one deer related death.

Weird people are more concentrated in the city - I say this as a social services worker. You are more at risk walking down the street than on a trail. The most danger will be at the trailhead - and that's a remote chance at best. I have gone alone backpacking without a qualm. Trail crime is a problem sometimes in places where people other than backpackers go hiking - I've heard anecdotes from folks about their tent disappearing in a backcountry Yosemite campground - but almost as rare as bear attacks.

I had friends who hunted mountain lions with dogs when the cats came down to kill calves and sheep. It was the only time we ever saw them...

No, I don't think you need a gun at all. Most trouble you might get into can be avoided by developing an awareness of your surroundings and a knowledge base that includes basic bear safety for the region, the habits of poisonous snakes in the area, and basic first aid to address various insect stings. You will also want some awareness of poison oak/ivy and how to get the oils out of your clothes... that's even more likely to "get" you than anything else.