That's quite the laundry list of animals to run into, and each requires their own precautions. Snakes and scorpions, just have bug netting and don't worry. Be careful where you step in camp, and that should be enough. I think scorpions glow under UV light, so if you really want to be paranoid, you can get a simple UV LED and check.

Bears, standard practice is to distribute your camp; I grew up camping in Yosemite, where the rules are you don't sleep where you cook, you don't store your food where you sleep, and you don't cook where you store your food. The three should be distributed 100 feet from each other. The food should, of course, be stored in a bear proof container, bears are clever enough that bear bags might not work. As long as the bag is hung a distance away from the camp, you are in very little danger, but the bear could eat your food. The bear proof canisters that some places require don't necessarily help you keep your food any better than a well hung bear bag, but it will stop the bear from getting your food at any cost. I've heard stories of bear canisters being found miles down the trail, and even more of them just vanishing, but none of them being cracked open. While on the macro scale this does lower the risk of humans being associated with food, it does very little to you personally.

If you are really paranoid about bears, you can always practice a total isolation policy, and have a separate set of clothing to eat in and to sleep in.

Boars have never bothered me, although I have had them sneaking around my camp at night looking for scraps.

Big cats, and Alligators, you are on your own, no experience.