It's just so narcissistic to think someone is out to get you. Are you a prosecutor in the Telly Hankton trial? Are you smuggling conflict diamonds? If the answer is no, you don't need a truck gun. No one wants to carjack your 2001 Chevy Silverado. The doctors and investment bankers and lawyers I know don't carry truck guns - only the redneck oilfield workers do. And you know what they do with them? They pull them out when they get drunk. I once saw a guy go out to his car in Tigerland to retrieve his Colt Python because he had been beaten up. Luckily he didn't blow anyone away.
I don't keep mine in when I go out to party. Never a good idea. I do carry because I sometimes have to work in the worst of New Orleans east, the 9th word or Gert town. It's rare, but I feel better armed out there. If anyone comes up to me while I am stopped or parked, my gun is out.
A person I knew's dad stopped in New Orleans east a few months back to look up directions to an apartment, he was robbed and killed. Not going to clean it up, but in some areas a white person in a halfway decent truck is an instant target. Cash, Credit Cards and tools and a whip.
So yes, I would advocate arming your vehicle.
Don't go pointing it around, but if someone coming to bum money from you or wash your windshield has other reasons and sees your hand on a pistol, they will back away.
I love New Orleans, but we have some hoods. I'm not willing to lose the bulk of my livelihood so I keep a gun in my truck.