I'm a long haul trucker, have been for 7 years.
I'm also a former LEO, and have a CHL good in many states, so I am pretty up to date and understanding of travel laws with firearms.
Short answer: Don't carry a weapon in your truck.
The industry as a whole looks at firearms in the cab as a serious offence, and you will usually get fired on the spot or your contract terminated immediately if your supervisors catch wind of this. We are routinely sent into the worst neighborhoods in the country, at all hours of the night. This is considered an "Non-Issue" by the companies. Driver safety, to them, means not hitting stuff with the truck.
Not so short answer: Follow these simple steps.
1) Life membership in the NRA. They will be the only one who gives a ratt's bottom when you get busted.
2) Pistols are a no-no, as many places outright ban them (Chicago, D.C.) and more places have bans on standard-capacity mags (over 10 rounds).
3) Hollow point ammo is a no-no. Again banned in some places, NJ comes to mind.
4) Leave the AR and SKS at home, these estabolish intent at 03:00 at a weigh station. Yeah, in Court it means nothing, but we want to stay out of the cuffs, much less court.
That really leaves 2 viable options. A shotgun or a revolver.
I might consider a shotgun, as it is not generally concealable, and when presented to a BG, really has a good psycological effect on them.
MILITARY BASES- Most of the bases I've been on give you an opportunity to declare any weapons you have and you can "check" them at the gate, pick them up when you leave.
PRIVATE PROPERTY- Nearly EVERY place I go nowadays has signs posted "No Firearms" "Dangerous Weapons Prohibited". In most cases these signs are legal and binding re: tresspassing laws. Also, many of these places have the "specific wording" signs like Texas' 30.06 sign prohibiting CCW on premesis.
Lastly, many of us go into Canada. Don't even want to think about the problems that's gonna cause.
Bottom line: I wouldn't carry a gun in the truck. That's not saying I haven't. That's not saying there aren't times when I wish I had.
But sooner or later, your boss is gonna find out one way or the other, and your job is toast (not to mention, you'll never drive for a reputable company again... DAC report? ANYONE??).
However, if you feel your need to self defense is that great, go ahead and carry. Also, I'd reccomend a different line of work. No one forces us to be out here. It's not like being secure in your home, or even in your town. It sucks, I know, but what ya gonna do?
:banghead: 
