I prefer a shot gun over a hand gun since its a lot easier to hit the target in a defensive situation. The sound of chambering a shell in a pump shot gun is more effective than the sound of cocking a revolver, or chambering a bullet in an automatic hand gun. Check out the laws of every state or country that you plan to travel though before taking the gun, whatever type it is. Many people like a noisy or trained security dog as a traveling companion. And they do provide some measure of protection.
Pets become vulnerable to fire when left unattended, as well as other health risks like overheating.
Most seasoned thieves know how to handle animals, and pets have proved to have limited effectiveness. True guard dogs have to be trained to be mean, and then kept separate from people to be effective guard dogs. Protecting your person and property outside your RV requires some planning too. Whistles, personal alarms, pepper spray, flashlights and other devices if carried properly, and if you are knowledgeable about their use, are all good things to consider. Self-defense training is also very good.