I have a Viper system and works great. It has a sensitivity control. If set too high it triggers on anything and can be very annoying. Even a bird landing on the truck, a twig falling off a tree, gunshot,fireworks, thunder, a rig driving by too close that makes the ground shake. The last thing you are going to want is your alarm going off and disturbing fellow campers with false triggers. Especially if you get a false trigger and you are not around to disable it. If your considering a proximity alarm any critter is going to trigger it. The Viper is my first line of defense. Triggers on a breakin and disables the starter. I also have several different size Pelican cases that can be locked and secured in the truck with concealed chains for personal valuables, firearms,etc. When boondocking I set up a trail cam covering the campsite. A picture is worth a thousand words to a Park Ranger especially if you get a tag number.
