I change truck guns almost as often as I change underwear. Some days it's 10/22, others a .243, still others my 22" Winchester 1300, we haven't even touched on my various handguns yet.
I believe a good pump shotgun should be one of the first guns people should get due to it's versatility. That versatility is the same whether it's in house or in the truck. It doesn't have to be tactical or combat style, just about any will due fine. Find a shortish barrel that accepts choke tubes and learn to use it.
If you're thinkin about keeping it 24/7 in your truck (I don't, my guns go inside with me for very good reasons) look hard for a Winchester 1300 Marine. They've been out of production for years but IMO the 1300's (any of them) operate very smooth and the stainless finish of the Marine will stand up better to corrosion. While the numbers don't show big differences, the 1300 handles lighter and faster than the Remingtons and Mossbergs.