Pocket pistol, or my more comfortable IWB snubbie, or other compacts, for trips to the local places.
Never left in the car overnight . However, I drive a work van with a drilled and tapped metal lock box in between the seats. It is like an ammo can with a stouter lid and key lock. I keep a pistol in there, unlock it when driving, lock it on service calls, van also has an alarm.
Generally, the shipyards, and marinas have gated security, it's the surrounding ghettos and industrial parks, that I drive through when I unlock the box, and keep it close.
In Riviera Beach, I even tuck it under my work shirt to get parts, re-fuel, etc,... It's a bad neighborhood.